Difference between revisions of "Map Transform"

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(Created page with "===Scanning a Background Map=== * '''Use a grid:''' In most cases you cannot scan the entire draft map (the background map). You are either limited by Windows (which limits the ...")
 
(Scanning a Background Map)
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===Scanning a Background Map===
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===Adjust the Map to the Background map===
  
* '''Use a grid:''' In most cases you cannot scan the entire draft map (the background map). You are either limited by Windows (which limits the maximum size of background maps), by the available memory, or by the size of the scanner (A4). In these cases it is strongly recommended that you should draw a grid on the draft map. In many cases there is already a kilometer grid which can be used. If this does not exist, you should draw a precise grid of vertical and horizontal lines (perhaps at a distance of 10 cm). Then the scanned pieces can be easily adjusted to fit the map in OCAD.
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This command is active when a background map is displayed.
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If more than one background map is open a dialog box is displayed where you can choose the desired background map.
  
* '''Resolution:''' As a general rule scan the map with 300 dpi.
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Choose this command to adjust the background map to the grid or to the part of the map you have already drawn. It is highly recommended to draw a precise grid on the draft map and then to use the crossing points of the grid for the adjustment (however, any points can be used for the adjustment). The '''grid button''' must be pressed to see the grid. You can use 1 to 12 points for the adjustment.  
  
* '''Scanning:''' If you have a scanner connected to your PC, and a 32-bit TWAIN driver is installed, then you choose the '''Scan''' command from the '''Background map''' menu to scan the background map.
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For each point you do the following:
If there is no TWAIN driver or you use a scanner on another PC, then use the scanner program which comes with the scanner and save the scanned background map as a BMP, GIF, JPEG or TIFF file. Choose '''Open''' from the '''Background map''' menu to open this file in OCAD.  
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# Mark the grid point on the background map.
Choose '''Adjust''' from the '''Background map''' menu to adjust the background map to the grid or to the part of the map you have already drawn. It is best to use 4 grid points (arranged in a rectangle) for the adjustment. This will compensate for rotation and any distortions of the draft.
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# Mark the same grid point on the grid displayed on the screen.
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When you have adjusted enough points, press the '''Enter''' key on the keyboard. The background map is rotated and stretched to get the best fit for the adjustment points.
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You can achieve a precise adjustment with 4 adjustment points arranged in a rectangle. This way you can compensate rotation and distortion. The horizontal and vertical scales will be adjusted individually.
  
Choose this command to scan a background map on a scanner connected to your PC. To use this command a 32-bit TWAIN driver must be installed for your scanner. If no TWAIN driver can be found, you should contact the vendor of your scanner to obtain a 32-bit TWAIN driver. See '''Scanning a background map''' for tips about scanning.
 
  
* '''Acquire submenu:''' Choose this submenu to start scanning. This command will show the main window of the TWAIN driver of your scanner. After scanning a file, a dialog box is displayed where you can enter a filename for the scanned background map. Then the scanned background map is opened.
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'''Select Transform from Map menu:'''
* '''Select source submenu:''' If more than one TWAIN source (or more than one driver) is installed, you can select in this submenu the desired source.
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* '''Move''' ADD
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* '''Stretch / Shrink''' ADD
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* '''Mirror''' ADD
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* '''Rotate Map''' ADD
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* '''Change coordinate System''' ADD
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'''Affine'''
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:''This function was called '''Transform Map''' before OCAD 10.2.3''
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Choose this command to adjust the whole map on background map or on grid. With this function you can geo-reference the map.
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The '''grid button''' must be pressed to see the grid.
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You can use 1 to 12 points for the adjustment. For each point you do the following:
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# Mark a point on map.
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# Mark the same grid point on reference (background map or grid.
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When you have adjusted enough points, press the '''Enter''' key on the keyboard. The map is rotated and stretched (Affine transformation) to get the best fit for the adjustment points.
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You can achieve a precise adjustment with 4 adjustment points arranged in a rectangle. This way you can compensate rotation and distortion. The horizontal and vertical scales will be adjusted individually.
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'''Rubbersheeting'''
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ADD picture
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: ''This function is only available in OCAD 10.2.4 and later''
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Choose this command to adjust a part of the map on a geo-referenced background map. The Rubbersheeting Transformation dialog box appears.
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# Define rubbersheeting perimeter: Click the Define button and define the perimeter by drawing a polyline on the map. To define a new rubbersheeting perimeter click the Remove button to remove the actual one.
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# Add rubbersheeting points: Click the Add button first and then click 2x on the map for each point:
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:: (1) Mark a point on the map.  
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:: (2) Mark the same point on the reference map. The rubbersheeting points are shown on the map by a red and a green cross and a connection line.
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:3. Calculate transformation: Calculate the rubbersheeting transformation: Click the Transform button.
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: [[File:Hint.jpg|hint]] -Click the '''Undo''' button if you are not satisfied with the rubbersheeting transformation.
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:: -Uncheck rubbersheeting points in the '''Used''' column if they should not be included in the transformation. Unchecked rubbersheeting points appear in gray color on the map.
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'''Center Map to Drawing Area'''
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Choose '''Transform''' in '''Map menu''' - '''Center Map to Drawing Area'''.
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This function is often used to center a map drawn in OCAD Professional edition into the smaller drawing area from OCAD Standard or CS edition. OCAD moves the map offset, all objects, all background maps and all bookmarks.  After this function the map is still geo-referenced.
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In the dialog the extent with the existing map offset is shown in grey, the extent with the new offset in blue. The green rectangle shows the drawing area of OCAD Professional edition (80x80m), the orange the drawing area from Standard edition (4x4m).
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If a map should be visible in all OCAD editions then the entire map must fit in the 4x4m drawing area.

Revision as of 15:24, 4 November 2011

Adjust the Map to the Background map

This command is active when a background map is displayed. If more than one background map is open a dialog box is displayed where you can choose the desired background map.

Choose this command to adjust the background map to the grid or to the part of the map you have already drawn. It is highly recommended to draw a precise grid on the draft map and then to use the crossing points of the grid for the adjustment (however, any points can be used for the adjustment). The grid button must be pressed to see the grid. You can use 1 to 12 points for the adjustment.

For each point you do the following:

  1. Mark the grid point on the background map.
  2. Mark the same grid point on the grid displayed on the screen.

When you have adjusted enough points, press the Enter key on the keyboard. The background map is rotated and stretched to get the best fit for the adjustment points. You can achieve a precise adjustment with 4 adjustment points arranged in a rectangle. This way you can compensate rotation and distortion. The horizontal and vertical scales will be adjusted individually.


Select Transform from Map menu:

  • Move ADD
  • Stretch / Shrink ADD
  • Mirror ADD
  • Rotate Map ADD
  • Change coordinate System ADD


Affine

This function was called Transform Map before OCAD 10.2.3

Choose this command to adjust the whole map on background map or on grid. With this function you can geo-reference the map. The grid button must be pressed to see the grid. You can use 1 to 12 points for the adjustment. For each point you do the following:

  1. Mark a point on map.
  2. Mark the same grid point on reference (background map or grid.

When you have adjusted enough points, press the Enter key on the keyboard. The map is rotated and stretched (Affine transformation) to get the best fit for the adjustment points. You can achieve a precise adjustment with 4 adjustment points arranged in a rectangle. This way you can compensate rotation and distortion. The horizontal and vertical scales will be adjusted individually.


Rubbersheeting

ADD picture

This function is only available in OCAD 10.2.4 and later

Choose this command to adjust a part of the map on a geo-referenced background map. The Rubbersheeting Transformation dialog box appears.

  1. Define rubbersheeting perimeter: Click the Define button and define the perimeter by drawing a polyline on the map. To define a new rubbersheeting perimeter click the Remove button to remove the actual one.
  2. Add rubbersheeting points: Click the Add button first and then click 2x on the map for each point:
(1) Mark a point on the map.
(2) Mark the same point on the reference map. The rubbersheeting points are shown on the map by a red and a green cross and a connection line.
3. Calculate transformation: Calculate the rubbersheeting transformation: Click the Transform button.
hint -Click the Undo button if you are not satisfied with the rubbersheeting transformation.
-Uncheck rubbersheeting points in the Used column if they should not be included in the transformation. Unchecked rubbersheeting points appear in gray color on the map.


Center Map to Drawing Area

Choose Transform in Map menu - Center Map to Drawing Area.

This function is often used to center a map drawn in OCAD Professional edition into the smaller drawing area from OCAD Standard or CS edition. OCAD moves the map offset, all objects, all background maps and all bookmarks. After this function the map is still geo-referenced. In the dialog the extent with the existing map offset is shown in grey, the extent with the new offset in blue. The green rectangle shows the drawing area of OCAD Professional edition (80x80m), the orange the drawing area from Standard edition (4x4m). If a map should be visible in all OCAD editions then the entire map must fit in the 4x4m drawing area.