DEM: Difference between revisions

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(/* Create Contour Lines File:Space.PNGThis function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartographyThis function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-...)
(/* Open File:Space.PNGThis function is available in OCAD Mapping Solution.|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 functi...)
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[[File:DEM.jpg]]
[[File:DEM.jpg]]


==Import [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
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.
 
The OCAD DEM Module is able to import files with regular and irregular DEM data. Supported DEM data formats are: ESRI ASCII Grid (*.asc), Raw data ASCII XYZ file (*.xyz), ASCII Grid XYZ file (*.xyz), LAS file (*.las) and SRTM file (*.hgt) file.
 
# Open a map or create a new one.
# Select '''Import''' from the '''DEM''' menu. First use '''Add''' button to add at least 1 DEM to the '''DEM Import''' dialog.
# '''Analyze''' the DEM to get some information about the DEM like extent, cell size etc. The '''DEM Import''' dialog extends after analyzing a LAS file and provides some additional settings.
# If the source file is a regular grid (data type of import files = grid), the '''Cell size''' box is set to read only. OCAD sets the same cell size for the imported DEM. For irregular DEM data source (data type of import files = raw) the cell size can be set in the 'cell size' box. For these DEM's OCAD interpolates a regular grid with the specified cell size during the import.
# At the end of the import procedure the imported DEM must be saved in the OCAD DEM file format (*.ocdDem) and it is loaded to the OCAD map.
# To see the extent of the loaded DEM activate the '''Show Frame''' menu item.
 
 
[[File:Hint.jpg|hint]] The '''Cell size''' range is between 0.01 and 650 m.<br>
[[File:Hint.jpg]] The DEM import limit depends on the amount of memory available. OCAD can allocate up to 3.5 GB RAM.
 
 
: [[File:DemImportLas.PNG]]
 
'''LAS data import:'''
* Click the '''Choose DTM''' button to create a terrain model from LAS data. This selects '''ground''' classification and the '''Last return''' option.
* Click the '''Choose DSM''' button to create a surface model from LAS data. This selects '''all classifications''' and the '''First return''' option.
[[File:Hint.jpg]] During LAS data import a classification image and a intensity image are created and loaded as background maps. A difference image between the first and last return is created if the '''All returns''' option in the DEM Import dialog is choosen.<br>
[[File:Hint.jpg]] A Radar beam splits as it hits objects. The result are multiple returns. LIDAR can collect up to four returns. The difference between first and last return can show object height. The last return doesn’t always reach the ground.


: [[File:DemImportLas MultipleReturn.jpg]]
: [[File:DemImportLas MultipleReturn.jpg]]
: Source: Lohani, Bharat. Airborne Altimetric LiDAR: Principle, Data Collection, Processing and Applications.
: Source: Lohani, Bharat. Airborne Altimetric LiDAR: Principle, Data Collection, Processing and Applications.


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


'''SRTM hgt data import:'''
==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]]==
* This is a world wide available DEM data set from the Shuttle Radar Topography Mission (SRTM).
* The data files and documentation: [http://dds.cr.usgs.gov/srtm/version2_1/]
[[File:Hint.jpg]] SRTM hgt data import requires that a coordinate system set in the OCAD map file.


==Open [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD 11 Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD 11 Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
Open an OCAD DEM file (*.ocdDem). OCAD 2020 can also open ocdDems created in OCAD 11 and OCAD 12.


Open an OCAD DEM file (*ocdDem).
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#Info|DEM Information dialog]].


==Show Frame [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD 11 Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD 11 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.


[[File:DemShowFrame.png]]


==Resize [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|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.


Resize the loaded OCAD DEM file (make a subset) and save it as a new OCAD DEM file.
[[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]]==


==Info [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD 11 Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD 11 Course Setting.|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 or overwrite the existing one.


Shows information about OCAD DEM file.
[[File:DemResize.png]]


[[File:Hint.jpg]] When moving the mouse cursor over the file name then the file name with path appears.
==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.


==Close [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD 11 Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD 11 Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
[[File:DemInfo.png]]


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


==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]]==


==Merge DEM [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
This function closes OCAD DEM file.


[[File:Merge.PNG|miniatur|400x400px|right]]
==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.


[[File:Merge.PNG]]


* '''DEM 1:''' Choose the first DEM.
* '''DEM 1:''' Choose the first DEM.
* '''DEM 2:''' Choose the second DEM.
* '''DEM 2:''' Choose the second DEM.


The two DEMs must have the same cell size.
==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.


[[File:Hint.jpg]] The two DEMs must have the same cell size and image clipping.
[[File:CalculateDEMDifference.PNG]]


==Calculate DEM Difference [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
Usually it is the difference between a terrain model and a surface model.
<BR>
[[File:CalculateDEMDifference.PNG|miniatur|400x400px|right]]


# Choose '''Calculate DEM Difference''' from '''DEM''' menu.
* Add ''Upper DEM'' = DSM data file
# The '''Calculate DEM Difference''' dialog box appears.
* Add ''Lower DEM'' = DTM data file
# Add ''Upper DEM'' = DSM data file
* Click '''OK'''.
# Add ''Lower DEM'' = DEM 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 '''[[DEM#Classify_Vegetation_Height|Classify Vegetation Height]]'''
To visualize the DEM difference choose '''[[DEM#Classify_Vegetation_Height|Classify Vegetation Height]]'''
Line 117: Line 102:
''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 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|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.
 
[[File:CreateContourLines.png]]
 
This function calculates contour lines based on the loaded DEM.
 
This function can take a lot of time. OCAD starts to calculate the contour lines from the lowest elevation (ninimun contour). During the calculation process the current elevation is shown in the left status bar.
 
*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).
: [[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]]
 
 
[[File:ContourLines.PNG]]
 
==Create Hypsometric Map [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
 
 
[[File:CreateHypsometricMap.PNG|miniatur|400x400px|right]]
 
:This function calculates a grayscale or colored hypsometric map as GeoTIFF file.
:Optionally it is directly loaded as background map.
 
 
Two different types of hypsometric maps can be edited:
 
* Grayscale hypsometric map
* Colored hypsometric map
 
[[File:HypsometricMap.PNG]]
 
==Create Hill Shading [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
 
[[File:CreateHillShading.PNG|miniatur|400x400px|right]]
 
:This function calculates a shaded relief picture (hill shading).
 
 
: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. Optionally the calculated hill shading is directly loaded as background map.
 
 
:Aside from the chosen method an '''Azimuth''' and a '''Declination''' of the light source has to be set. Standard settings are 315° (north-west) and 45°. An '''Exaggeration''' factor of 4 is pre-selected and can be altered.
 
[[File:HillShading.PNG]]
 
==Calculate Slope Gradient [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
 
 
[[File:CalculateSlopeGradient.PNG]]


:Choose '''Calculate Slope Gradient''' from '''DEM''' menu.
Choose '''Create Contour Lines''' from '''DEM''' menu. The '''Create Contour Lines''' dialog box appears.  
:The '''Calculate Slope Gradient''' dialog box appears.


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


Select one of two different methods:
==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]]==


* Continous (<x° = grayscale / >x° = black)
Choose '''Create Hypsometric Map''' from '''DEM''' menu. The '''Create Hypsometric Map''' dialog box appears.
* 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).
Read more about this function on the page [[DEM Import Wizard#Create Hypsometric Map|DEM Import Wizard]].


Slope gradient also shows paths or relief features independent from a azimut like the [[DEM#Create_Hill_Shading|Hill Shading]].
==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:SlopeGradient.PNG]]
Choose '''Create Hill Shading''' from '''DEM''' menu. The '''Create Hill Shading''' dialog box appears.


==Classify Vegetation Height [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|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]].


[[File:DemClassifyVegetationHeight.PNG|miniatur|400x400px|right]]
==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]]==


Choose '''Classify Vegetation Height''' from '''DEM''' menu.
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#Calculate Slope Gradient|DEM Import Wizard]].


There are two different options to show vegetation height classification:
==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]]==


* Gray scale classification with options: Linear, Quadratic negative, Quadratic positive
Choose '''Classify Vegetation Height''' from '''DEM''' menu. The '''Classify Vegetation Height''' dialog box appears.
* Colored classification: Define classes with a height and color range
: - Split a class into two classes by clicking the '''Split class''' button
: - Remove a class by clicking the '''Remove class''' button
: - 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]]
Read more about this function on the page [[DEM Import Wizard#Classify Vegetation Height|DEM Import Wizard]].
 
 
==Merge Contour Lines By Selected Symbols [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==


==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.
* Choose '''Merge Contour Lines By Selected Symbols''' from DEM menu.
* The '''Merge Contour Lines By Selected Symbols''' dialog box appears.
* The '''Merge Contour Lines By Selected Symbols''' dialog box appears.
Line 216: Line 140:
[[File:MergeContourLinesBySelectedSymbols.png]]
[[File:MergeContourLinesBySelectedSymbols.png]]


==Create Profile [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:Sta40px.PNG|This function is available in OCAD 11 Starter.|link=https://www.ocad.com/en/products/ocad-for-orienteering]][[File:CS40px.PNG|This function is available in OCAD 11 Course Setting.|link=https://www.ocad.com/en/products/ocad-for-orienteering]]==
==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]]
[[File:ProfileExample.PNG|600px]]


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


==Export [[File:Space.PNG]][[File:Pro40px.PNG|This function is available in OCAD 11 Professional.|link=https://www.ocad.com/en/products/ocad-for-cartography]][[File:Std40px.PNG|This function is available in OCAD 11 Orienteering Standard.|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]]==  


* Choose '''Export''' from DEM menu.
* Choose '''Export''' from DEM menu.
Line 228: Line 152:
[[File:DEMExport.PNG]]
[[File:DEMExport.PNG]]


The function exports the loaded DEM file as ESRI ASCII Grid or as ASCII Grid XYZ.
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


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 '''LiDAR Point Cloud Manager''' analyzes the vegetation within the forest and creates a vegetation raster map.
Previous Chapter: '''[[Printing Maps]]'''
Learn more on the '''[[LiDAR Point Cloud Manager]]''' page.


Next Chapter: '''[[GPS]]'''


Back to the '''[[Main Page]]'''
----
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Revision as of 13:48, 1 April 2020

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

DEM.jpg

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.

DemImportLas MultipleReturn.jpg
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 2020 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.

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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