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Windows 10 64-bit (64.0 GB RAM - Intel Xeon W-2133 CPU @ 3.60GHz)
Global Mapper Version
  • How to digitize contour line in an efficient way

    1. Make sure you have assigned the elevations first then (Vertex Editing > Edit Feature Vertices)
    2. Select the lines
    3. Right-click
    4. Advanced Feature Creation Options > Create Point Features Spaced Along Selected Features

    Alternatively, if you have reasonably clean contours you may be able to convert them to lines by creating area features based on the contour colour values and then converting those to center lines:

    1. Right-click the raster layer
    2. Create Area Features from Equal Values in Selected Layer
    3. Choose Only Create Areas for Selected Colors and enter the RGB value of your contour e.g. 0,0,0 for black
    4. Select the newly created area features
    5. Right-click > Move/Reshape Feature(s) > SIMPLIFY
    6. Right-click > Move/Reshape Feature(s) > SMOOTH
    7. Right-click > Advanced Feature Creation Options > Create Area Skeletons/Center Lines
    8. Join any gaps in the new contour lines:
    9. Right-click > Crop/Combine/Split Functions > COMBINE 
    10. Repeat steps 5 & 6 to reduce the points and smooth

    This is an example I created using the above workflow - took around 10-15 minutes. Using the Image Swipe Tool I have shown the original raster on the right and the results of the process above on the left. The image below that shows the raster below the new contour lines.

  • Combine terrain - coloring based on change

    1- Original terrain with dump artificially flattened for illustrative purposes

    02 - New terrain with higher dump and 3 small artificially flattened areas to the west (this is so we can also show cut as well as fill later)

    03 - Combine/Compare Terrain Layers. Use Subtraction (Signed) and select New then Old. We use Signed so that we can see negative cut values as well as positive fill values.

    04 - Your result will look like this with the Atlas shader. Orange or 0m illustrates no change.

    05 - Create new 'Change' shader

    06 - Define as follows or choose your preferred colours. I've used red for fill and blue for cut. No change is set to white but do not use a different colour for this. When using the blend mode later it will become transparent.

    07 - Turn on the 'New' terrain layer and switch to the Daylight shader (use white as Surface Color - see Surface Color button in the image for step 05 at the top)

    08 - Turn on Combined Elevation terrain layer and double click it and go to the Display tab. Change the Blend Mode, select the custom shader called 'Change' and turn off the hill shading effects.

    09 - The following steps will be required if you wish to render a 3D view with the colouring applied. Unfortunately the above does not work in 3D view; only in plan.

    To begin Right-click on the Combined Elevation layer then Layer > Export and choose JPG2000 or similar image format. Make sure to check PRJ in the options. Do not export as an elevation grid though as we just want the colours.

    10 - Import the layer back in and double click it and go to the Display tab. Check the Texture Map option to apply the colour to the terrain. This can also be done via the Blend Mode if you choose.

    11 - Hit the 3D button on the main toolbar and capture your image using the Save Image button (Camera button on toolbar)

    Good luck!