DEM: Difference between revisions

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(/* Open File:Space.PNGThis function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartographyThis function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteeringThis function i...)
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A DEM (Digital Elevation Model) contains points with elevation data. DEM Data are based on LIDAR (Light Detection and Ranging) technology measurement, also known as Airborne Laser Scanning. There are DEM with point data arranged in a regular grid with a constant distance between the points. This distance is called cell size. Other DEM contain data points arranged irregularly (cloud-model).
A DEM (Digital Elevation Model) contains points with elevation data. DEM Data are based on LiDAR (Light Detection and Ranging) technology measurement, also known as Airborne Laser Scanning. There are DEM with point data arranged in a regular grid with a constant distance between the points. This distance is called cell size. Other DEM contain data points arranged irregularly (cloud-model).
: Read more about this topic: http://en.wikipedia.org/wiki/Digital_elevation_model
Read more about this topic: http://en.wikipedia.org/wiki/Digital_elevation_model


[[File:DEM.jpg]]
[[File:Lidar.png|1000px]]<br>
''Left picture'': LiDAR systems emit laser pulses and detect the light scattered back from the atmosphere. The distance to the location of the scattering is calculated from the light travel time of the signals<br>
''Middle picture'': A laser beam splits as it hits objects. The result are multiple returns. The last return doesn’t always reach the ground.<br>
''Right picture'': The difference between first return (Digital Surface Model DSM) and last return (Digital Terrain Model DTM) can show object height.<br>
''Source: Lohani, Bharat. Airborne Altimetric LiDAR: Principle, Data Collection, Processing and Applications.''


A laser beam splits as it hits objects. The result are multiple returns. The difference between first and last return can show object height. The last return doesn’t always reach the ground.
==DEM Import Wizard [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
 
: [[File:DemImportLas MultipleReturn.jpg]]
: Source: Lohani, Bharat. Airborne Altimetric LiDAR: Principle, Data Collection, Processing and Applications.
 
==DEM Import Wizard==
Read more about importing DEM file on the page [[DEM Import Wizard]].
Read more about importing DEM file on the page [[DEM Import Wizard]].


==Open [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==Open [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Open an OCAD DEM file (*.ocdDem). OCAD 12 can also open ocdDems created in OCAD 11.
Open an OCAD DEM file (*.ocdDem). OCAD 2018 can also open ocdDems created in OCAD 11 and OCAD 12.


The OCAD DEM file is a DEM grid in an OCAD internal file format created in the [[DEM Import Wizard]].  
The OCAD DEM file is a DEM grid in an OCAD internal file format created in the [[DEM Import Wizard]].  
This file is optimized for fast access to the height values.
This file is optimized for fast access to the height values.


For more information (e.g. cell size) about this file open the [[DEM Import Wizard#Info|DEM Information dialog]].
For more information (e.g. cell size) about this file open the [[DEM#Info|DEM Information dialog]].


==Show Frame [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==Show Frame [[File:Space.PNG]][[File:Mas40px.png|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Shows blue rectangle with the extent of the loaded DEM.
Shows blue rectangle with the extent of the loaded DEM.
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[[File:DemShowFrame.png]]
[[File:DemShowFrame.png]]


==Resize [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
When moving the mouse cursor inside the frame the height values is show in the status bar together with the coordinate.
 
[[File:DemShowFrameStatusBar.png]]
 
==Resize [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Resize the loaded OCAD DEM file (make a subset) and save it as a new OCAD DEM file.
Resize the loaded OCAD DEM file (make a subset) and save it as a new OCAD DEM file or overwrite the existing one.


[[File:DemResize.png]]
[[File:DemResize.png]]


==Info [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==Info [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Shows information about OCAD DEM file.
Shows information about OCAD DEM file.
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When moving the mouse cursor over the file name then the file name with path appears.
When moving the mouse cursor over the file name then the file name with path appears.


==Close [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==Close [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Close OCAD DEM file.
This function closes OCAD DEM file.


==Merge DEM [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==Merge DEM [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Choose '''Merge''' from '''DEM''' menu to merge two different DEMs.
Choose '''Merge''' from '''DEM''' menu to merge two different DEMs.
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The two DEMs must have the same cell size.
The two DEMs must have the same cell size.


==Calculate DEM Difference [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==Calculate DEM Difference [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
Choose '''Calculate DEM Difference''' from '''DEM''' menu. The '''Calculate DEM Difference''' dialog box appears.
Choose '''Calculate DEM Difference''' from '''DEM''' menu. The '''Calculate DEM Difference''' dialog box appears.


[[File:CalculateDEMDifference.PNG]]
[[File:CalculateDEMDifference.PNG]]
Usually it is the difference between a terrain model and a surface model.


* Add ''Upper DEM'' = DSM data file
* Add ''Upper DEM'' = DSM data file
* Add ''Lower DEM'' = DEM data file
* Add ''Lower DEM'' = DTM data file
* Click '''OK'''.
* Click '''OK'''.
In the [[DEM Import Wizard]] it is possible to import DTM and DSM and create the DEM difference in one step.


To visualize the DEM difference choose '''[[DEM#Classify_Vegetation_Height|Classify Vegetation Height]]'''
To visualize the DEM difference choose '''[[DEM#Classify_Vegetation_Height|Classify Vegetation Height]]'''
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''Data source: Test data Wabern from swisstopo.''
''Data source: Test data Wabern from swisstopo.''


==Create Contour Lines [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==Create Contour Lines [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Choose '''Create Contour Lines''' from DEM menu. The '''Create Contour Lines''' dialog box appears.  
Choose '''Create Contour Lines''' from '''DEM''' menu. The '''Create Contour Lines''' dialog box appears.  


[[File:CreateContourLines.png]]
Read more about this function on the page [[DEM Import Wizard#Create Contour Lines|DEM Import Wizard]].


This function calculates contour lines based on the loaded DEM.  
==Create Hypsometric Map [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


This function can take a lot of time. OCAD starts to calculate the contour lines from the lowest elevation (minimun contour). During the calculation process the current elevation is shown in the left status bar.
Choose '''Create Hypsometric Map''' from '''DEM''' menu. The '''Create Hypsometric Map''' dialog box appears.


*Define 1-3 contour intervals (for example 1m, 5m, 25m) and a pre-selected line symbol (according to the first three line symbols in the settings) for each type appears (can be changed).
Read more about this function on the page [[DEM Import Wizard#Create Hypsometric Map|DEM Import Wizard]].
: [[File:Hint.jpg]] Contour interval values can be entered manually or chosen from the list.
*Specify the minimum (lowest) and maximum (highest) contour for the calculation.
* Activate the option '''Split DEM into tiles''' to speed up this calculate process. In this case OCAD splits the dem into small tiles and calculates tile by tile. Finally the contour lines are also splites at the tile borders. It is not visible on the screen but you see it when selecting a contour line. Use the [[DEM#Merge_Contour_Lines_By_Selected_Symbols|Merge Contour Lines By Selected Symbols]] function to merge the contour lines if needed.
[[File:ContourLinesSplitted.PNG]]


The selected contour line is cutted at the tile borders.
==Create Hill Shading [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


[[File:ContourLines.PNG]]
Choose '''Create Hill Shading''' from '''DEM''' menu. The '''Create Hill Shading''' dialog box appears.


==Create Hypsometric Map [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
Read more about this function on the page [[DEM Import Wizard#Create Hill Shading|DEM Import Wizard]].


==Calculate Slope Gradient [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


[[File:CreateHypsometricMap.PNG|miniatur|400x400px|right]]
Choose '''Calculate Slope Gradient''' from '''DEM''' menu. The '''Calculate Slope Gradient''' dialog box appears.


:This function calculates a grayscale or colored hypsometric map as GeoTIFF file.
Read more about this function on the page [[DEM Import Wizard#Calculate Slope Gradient|DEM Import Wizard]].
:Optionally it is directly loaded as background map.


==Classify Vegetation Height [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Two different types of hypsometric maps can be edited:
Choose '''Classify Vegetation Height''' from '''DEM''' menu. The '''Classify Vegetation Height''' dialog box appears.


* Grayscale hypsometric map
Read more about this function on the page [[DEM Import Wizard#Classify Vegetation Height|DEM Import Wizard]].
* Colored hypsometric map


[[File:HypsometricMap.PNG]]
==Merge Contour Lines By Selected Symbols [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
This is an obsolete function. It is still in the latest OCAD version due to compability issues. OCAD merges the contour lines automatically.
* Select the contour line symbols
* Choose '''Merge Contour Lines By Selected Symbols''' from DEM menu.
* The '''Merge Contour Lines By Selected Symbols''' dialog box appears.


==Create Hill Shading [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
[[File:MergeContourLinesBySelectedSymbols.png]]


[[File:CreateHillShading.PNG|miniatur|560x360px|right]]
==Create Profile [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
[[File:ProfileExample.PNG|600px]]


:This function calculates a shaded relief picture (hill shading).
Find more information about this function on the '''[[DEM Profile]]''' page.
 
 
:There are two calculation methods available:
* '''Slope shading''' is optimized to see outlines of features like paths in a slope.
* '''Slope shading combined with oblique light shading''' is the recommended method if the hill shading should be used as a background relief of a map.<br>Optionally the calculated hill shading is directly loaded as background map.
 
:Aside from the chosen method, there is to define the '''Resolution''' and the '''Interpolation''' mode (if chosen).
::The default interpolation mode is Bicubic, but there are 7 other algorithm.
:Additionaly an '''Azimuth''' and a '''Declination''' of the light source has to be set. Standard settings are 315° (north-west) and 45°.<br>An '''Exaggeration''' factor of 4 is pre-selected and can be altered.
 
The '''Preview...''' button allows you get a first impression of the current setting for your hillshading and can be use to optimize it.
::Click and move with the left mouse button allows to pan the current view.
The '''Preview...''' button is only enabeld when importing a dem grid file or an ocddem is already loaded. This function is disabled when importing las/laz files.
 
 
[[File:Hint.jpg|hint]]To detect point and line objects like paths or watercourses from DEM we recommend using the same resolution as the DEM. To create a relief and if the DEM cell size isn’t high then we recommend to set a smaller resolution.
 
 
[[File:Hint.jpg|hint]]The default export file format is JPEG and creates an 8 bit JPEG with in grayscale and a world file with the geo reference. If you decide to export the file in TIFF-format, only with resolution option ‘DEM cell size’ then OCAD creates an 8 bit grayscale tiff with color palette. Otherwise a 24 bit RGB tiff.
[[File:HillShading.PNG]]
===Error Message ''Bitmap is too big''===
The size of the hill shading image is limited. If this error message appears please enter a bigger value for the interpolation.
 
==Calculate Slope Gradient [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
 
 
[[File:CalculateSlopeGradient.PNG]]
 
:Choose '''Calculate Slope Gradient''' from '''DEM''' menu.
:The '''Calculate Slope Gradient''' dialog box appears.
 
 
Select one of two different methods:
 
* Continous (<x° = grayscale / >x° = black)
* Black/White (<x° = white / >x° = black)
 
The resulting picture can be used to identify cliffs an rock faces. The result can sometimes be significantly improved with a slight adjustment of the gradient (between 42-45 degrees).
 
Slope gradient also shows paths or relief features independent from a azimut like the [[DEM#Create_Hill_Shading|Hill Shading]].
 
[[File:SlopeGradient.PNG]]
 
==Classify Vegetation Height [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
 
[[File:DemClassifyVegetationHeight.PNG|miniatur|400x400px|right]]


Choose '''Classify Vegetation Height''' from '''DEM''' menu.
==Create optimized DEM for Course Setting [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
[[File:OptimizedDEMSettings.png]]


The DEM is typically created by the map maker as a basis for mapping. Course setters need a DEM to run the '''[[Route_Analyzer|Route Analyzer]]'''.
The DEM can passed on to the course setters as an optimized and compressed Course Setting DEM (ocdCsDem), which has greatly reduced file size with no quality loss for route calculation. In addition, the optimized DEM can be embedded directly into the map file or course setting file to make exchange easier.


There are two different options to show vegetation height classification:
===DEM files===
*'''Use loaded DEM''': If a DEM is already loaded, you can use it to create an optimized DEM.
*'''Use DEM(s) from folder''': Click the '''Add''' button to choose DEM files from a folder. You can choose multiple DEM files, but be aware that the grid size need to be the same. Click the '''Remove all''' button to remove the files from the list again.


* Gray scale classification with options: Linear, Quadratic negative, Quadratic positive
===Optimized DEM===
* Colored classification: Define classes with a height and color range
*'''Embed into the map file''': Select this option to embed the optimized DEM directly into the file. You can embed the DEM into the map file or course setting file. The file size will increase.
: - Split a class into two classes by clicking the '''Split class''' button
*'''Save as external DEM file''': Save the optimized DEM as external file after its creation. When passing the course setting project to another person, make sure that the external DEM is also sent.
: - Remove a class by clicking the '''Remove class''' button
*'''Load (Instead of currently loaded)''': In OCAD, only one DEM can be loaded at the same time. When you create the optimized DEM, you can load it directly instead of the currently loaded (non-optimized) DEM.
: - Load the settings from a text file by clicking the '''Load''' button
: - Save the settings to a text file by clicking the '''Save''' button
: - Reset the classes and colors to the default settings by clicking the '''Reset classes to default''' button


[[File:VegetationHeightGrayAndColor.PNG]]
==Remove embedded DEM [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


Click this function to removed an embedded DEM.<br>
Run the '''[[Map#Optimize_and_Repair|Optimize and Repair]]''' command afterwards to reduce the file size again.


==Merge Contour Lines By Selected Symbols [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==Export [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==  
This is an obsolete function. It is still in OCAD 12 due to compability issues. OCAD 12 merges the contour lines automatically.
* Select the contour line symbols
* Choose '''Merge Contour Lines By Selected Symbols''' from DEM menu.
* The '''Merge Contour Lines By Selected Symbols''' dialog box appears.
 
[[File:MergeContourLinesBySelectedSymbols.png]]
 
==Create Profile [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
[[File:ProfileExample.PNG|600px]]
 
Find more information about this function on the '''[[DEM Profile]]''' page.
 
==Export [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==  


* Choose '''Export''' from DEM menu.
* Choose '''Export''' from DEM menu.
Line 220: Line 173:
The function exports the loaded DEM file to the following formats:
The function exports the loaded DEM file to the following formats:
* ESRI ASCII Grid  
* ESRI ASCII Grid  
::Select '''Create tiles''' for large DEMs to create tiles from 1001x1001 points.
* ASCII Grid XYZ
* ASCII Grid XYZ
* OCAD 11 DEM


Select '''Create tiles''' for large DEMs to create tiles fron 1001x1001 points.
==LiDAR Point Cloud Manager [[File:Space.PNG]][[File:Mas40px.PNG|This function is available in OCAD Mapping Solution.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Ori40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


The OCAD 12 DEM's cannot be opened in OCAD 11. This export function creates a OCAD 11 compatible DEM.
The '''LiDAR Point Cloud Manager''' analyzes the vegetation within the forest and creates a vegetation raster map.
 
Learn more on the '''[[LiDAR Point Cloud Manager]]''' page.
==ocdLas File [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD Orienteering.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
 
Learn more about the '''ocdLas File''' functions on the '''[[ocdLas File]]''' page.




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Back to [[Main Page]]
Back to [[Main Page]]
Previous Chapter: [[Printing Maps]]
Next Chapter: [[GPS]]

Latest revision as of 19:07, 4 December 2023

A DEM (Digital Elevation Model) contains points with elevation data. DEM Data are based on LiDAR (Light Detection and Ranging) technology measurement, also known as Airborne Laser Scanning. There are DEM with point data arranged in a regular grid with a constant distance between the points. This distance is called cell size. Other DEM contain data points arranged irregularly (cloud-model). Read more about this topic: http://en.wikipedia.org/wiki/Digital_elevation_model

Lidar.png
Left picture: LiDAR systems emit laser pulses and detect the light scattered back from the atmosphere. The distance to the location of the scattering is calculated from the light travel time of the signals
Middle picture: A laser beam splits as it hits objects. The result are multiple returns. The last return doesn’t always reach the ground.
Right picture: The difference between first return (Digital Surface Model DSM) and last return (Digital Terrain Model DTM) can show object height.
Source: Lohani, Bharat. Airborne Altimetric LiDAR: Principle, Data Collection, Processing and Applications.

DEM Import Wizard Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Read more about importing DEM file on the page DEM Import Wizard.

Open Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.This function is available in OCAD Starter.This function is available in OCAD Course Setting.

Open an OCAD DEM file (*.ocdDem). OCAD 2018 can also open ocdDems created in OCAD 11 and OCAD 12.

The OCAD DEM file is a DEM grid in an OCAD internal file format created in the DEM Import Wizard. This file is optimized for fast access to the height values.

For more information (e.g. cell size) about this file open the DEM Information dialog.

Show Frame Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.This function is available in OCAD Starter.This function is available in OCAD Course Setting.

Shows blue rectangle with the extent of the loaded DEM.

DemShowFrame.png

When moving the mouse cursor inside the frame the height values is show in the status bar together with the coordinate.

DemShowFrameStatusBar.png

Resize Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Resize the loaded OCAD DEM file (make a subset) and save it as a new OCAD DEM file or overwrite the existing one.

DemResize.png

Info Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.This function is available in OCAD Starter.This function is available in OCAD Course Setting.

Shows information about OCAD DEM file.

DemInfo.png

When moving the mouse cursor over the file name then the file name with path appears.

Close Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.This function is available in OCAD Starter.This function is available in OCAD Course Setting.

This function closes OCAD DEM file.

Merge DEM Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Choose Merge from DEM menu to merge two different DEMs.

Merge.PNG

  • DEM 1: Choose the first DEM.
  • DEM 2: Choose the second DEM.

The two DEMs must have the same cell size.

Calculate DEM Difference Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Choose Calculate DEM Difference from DEM menu. The Calculate DEM Difference dialog box appears.

CalculateDEMDifference.PNG

Usually it is the difference between a terrain model and a surface model.

  • Add Upper DEM = DSM data file
  • Add Lower DEM = DTM data file
  • Click OK.

In the DEM Import Wizard it is possible to import DTM and DSM and create the DEM difference in one step.

To visualize the DEM difference choose Classify Vegetation Height

Hint.jpg The extent of the Upper DEM and Lower DEM can be different. OCAD takes the overlapping area for the new DEM.

Hint.jpg The cell size of Upper DEM and Lower DEM can be different. OCAD takes the cell size of Upper DEM for the new DEM.

Example

This is an example to show what can result from the Calculate DEM Difference function.

This is a DTM (Digital Terrain Model) with a cell size of 5m shown as hypsometric map:

DTM5mHypso.PNG

The next picture shows the DSM (Digital Surface Model) of the same area with a cell size of 2m as hypsometric map. The buildings (northern part) and forest (south western part) are slightly visible.

DSM2mHypso.PNG

The next picture shows a Difference DEM with a cell size of 2m shown as raster background map after calculating the DEM Difference. In addition, heights were colored using the Classify Vegetation Height function.

ClassifiedDifferenceDEM.PNG

  • The area with no difference of the DTM and the DSM are displayed white.
  • A height difference up to 15m appears red.
  • The greater the difference, the greener an area appears.

When moving the mouse cursor over the map the difference is shown in the Status Bar.

Data source: Test data Wabern from swisstopo.

Create Contour Lines Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Choose Create Contour Lines from DEM menu. The Create Contour Lines dialog box appears.

Read more about this function on the page DEM Import Wizard.

Create Hypsometric Map Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Choose Create Hypsometric Map from DEM menu. The Create Hypsometric Map dialog box appears.

Read more about this function on the page DEM Import Wizard.

Create Hill Shading Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Choose Create Hill Shading from DEM menu. The Create Hill Shading dialog box appears.

Read more about this function on the page DEM Import Wizard.

Calculate Slope Gradient Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Choose Calculate Slope Gradient from DEM menu. The Calculate Slope Gradient dialog box appears.

Read more about this function on the page DEM Import Wizard.

Classify Vegetation Height Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

Choose Classify Vegetation Height from DEM menu. The Classify Vegetation Height dialog box appears.

Read more about this function on the page DEM Import Wizard.

Merge Contour Lines By Selected Symbols Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

This is an obsolete function. It is still in the latest OCAD version due to compability issues. OCAD merges the contour lines automatically.

  • Select the contour line symbols
  • Choose Merge Contour Lines By Selected Symbols from DEM menu.
  • The Merge Contour Lines By Selected Symbols dialog box appears.

MergeContourLinesBySelectedSymbols.png

Create Profile Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.This function is available in OCAD Starter.This function is available in OCAD Course Setting.

ProfileExample.PNG

Find more information about this function on the DEM Profile page.

Create optimized DEM for Course Setting Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.This function is available in OCAD Starter.This function is available in OCAD Course Setting.

OptimizedDEMSettings.png

The DEM is typically created by the map maker as a basis for mapping. Course setters need a DEM to run the Route Analyzer. The DEM can passed on to the course setters as an optimized and compressed Course Setting DEM (ocdCsDem), which has greatly reduced file size with no quality loss for route calculation. In addition, the optimized DEM can be embedded directly into the map file or course setting file to make exchange easier.

DEM files

  • Use loaded DEM: If a DEM is already loaded, you can use it to create an optimized DEM.
  • Use DEM(s) from folder: Click the Add button to choose DEM files from a folder. You can choose multiple DEM files, but be aware that the grid size need to be the same. Click the Remove all button to remove the files from the list again.

Optimized DEM

  • Embed into the map file: Select this option to embed the optimized DEM directly into the file. You can embed the DEM into the map file or course setting file. The file size will increase.
  • Save as external DEM file: Save the optimized DEM as external file after its creation. When passing the course setting project to another person, make sure that the external DEM is also sent.
  • Load (Instead of currently loaded): In OCAD, only one DEM can be loaded at the same time. When you create the optimized DEM, you can load it directly instead of the currently loaded (non-optimized) DEM.

Remove embedded DEM Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.This function is available in OCAD Starter.This function is available in OCAD Course Setting.

Click this function to removed an embedded DEM.
Run the Optimize and Repair command afterwards to reduce the file size again.

Export Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

  • Choose Export from DEM menu.
  • The DEM Export dialog box appears.

DEMExport.PNG

The function exports the loaded DEM file to the following formats:

  • ESRI ASCII Grid
Select Create tiles for large DEMs to create tiles from 1001x1001 points.
  • ASCII Grid XYZ

LiDAR Point Cloud Manager Space.PNGThis function is available in OCAD Mapping Solution.This function is available in OCAD Orienteering.

The LiDAR Point Cloud Manager analyzes the vegetation within the forest and creates a vegetation raster map. Learn more on the LiDAR Point Cloud Manager page.


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