- Last Active
- No Roles
- Windows Version
- Windows 10 64-bit (64.0 GB RAM - Intel Xeon W-2133 CPU @ 3.60GHz)
- Global Mapper Version
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)
You can smooth the contours after they have been generated.
- Select them with the Digitizer Tool
- Right-click > Move/Reshape Feature(s) > Resample/Split Selected Features(s) at Specified Spacing
- Choose Sample Features at Fixed Distance Interval
- Enter the Spacing Distance e.g. 5 or 10 meters
- With the contours still selected Right-click > Move/Reshape Feature(s) > Smooth
By the way if you want to clip the SRTM to your boundary you can select the boundary be fore you select the online data source and choose the option at the bottom to Download Within the Currently Selected Polygon(s).