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Digitizing using Cartalinx

Digitizing using Cartalinx. Cartalinx. Database development and topological editing software Creates vector coverages from digitized maps along with associated attribute tables Companion Software to IDRISI. Getting Started. Tape paper map to digitizing tablet

katherinecunningham
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Digitizing using Cartalinx

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  1. Digitizing using Cartalinx

  2. Cartalinx • Database development and topological editing software • Creates vector coverages from digitized maps along with associated attribute tables • Companion Software to IDRISI

  3. Getting Started • Tape paper map to digitizing tablet • Find the scale of the map and the coordinate system, and make note of them • Open Cartalinx • Open New Coverage from file menu and choose create blank coverage. - The following screen will now appear…

  4. Map Coordinates

  5. Map Coordinates (steps) • Enter extent of paper map • Enter coordinate system (if known e.g UTM, followed by zone ID) • Select OK

  6. Setting Tolerances and Puck Options • Acceptable RMS = 1 metre of Total RMSE for each 25000 of scale denominator. • E.g. , scale = 1:25 000, acceptable RMSE = 10.0 m. • Determine RMSE threshold for your map • Click on the Select Tolerances icon at the top of the screen (see following slide)

  7. Set Toloerances Set Tolerances

  8. Set Tolerances • Node snap tolerance = 1 * RMSE (check show snap circles) • Set Feature Selection Tolerance equal to 2 * RMSE (check show selection circles) • Vertex weed tolerance – used for digitizing streams…leave blank for now.

  9. Tablet Button map

  10. Digitizer Puck • Buttons on Tablet Button Map do NOT correspond to the number on the puck. • Button map numbers start with 1 as the top left button (actually labelled 0 on the puck, and go through to 16 at the bottom right (actually labelledfon the puck.

  11. GCPs • Once tolerances have been set, select register digitizing tablet from the Digitize menu. Choose Define Map Transformation • Select GCPs on your map and record coordinates (as in lab 1). Cartalinx demands a minimum of six, but more points will provide greater accuracy. Make sure you label your points (i.e. 1, 2, 3, etc.) • Enter # of control points selected on your map, followed by the coordinates of each • Select Digitize Board coordinates

  12. GCP selection

  13. Digitizing GCPs • Place puck’s crosshairs on starting on control point 1, and press the select vertex button (currently button 0 on the puck). • Continue in order until all GCPs are entered • The RMSE will be displayed. To continue, it should be below your desired threshold. If not, you will have to re-digitize your control points, or select additional GCPs. • Save GCP file so you do not have to redo this next time you work on the same map

  14. Selecting Input Device mouse Digitizing puck

  15. Input Devices • After successful registration of the map, the input device should be set to the digitizer • Use puck to digitize desired coverages • Use mouse to select and build polygons, select and move nodes

  16. Digitizing a Feature • Begin digitizing by starting a node (button 1 on puck) • Digitize vertices of feature by pressing add vertex button (button 0) whenever the feature changes direction • Note: you may wish to zoom in if you are having trouble seeing what you are doing • To finish an arc, press 1 again. • If you wish to close a polygon, press b button when you have returned to the start node

  17. Polygons • To see if you have successfully created a polygon, digitize a polygon locator • Switch to the mouse • Digitize polygon locator node within your polygon by pressing cntrl + left click. • Go to coverage and select build polygons. • If successful, the polygon should be filled with solid colour and polygon should be added to the polygon attribute table (left portion of screen) • Note: Polygon Locator can also be used in digitizer mode by pressing the A button on the puck within the polygon

  18. And Remember… • SAVE, SAVE, SAVE…(file, save..) • The help function is fairly intuitive….you’ll likely need it!

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