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- Windows 10 64-bit (64.0 GB RAM - Intel Xeon W-2133 CPU @ 3.60GHz)
- Global Mapper Version
You can add 3D distance attributes to selected lines using Analysis/Measurement > Calculate Elevation/Slope Stats for Selected Feature(s) and choosing NO - Sample Terrain Along Path to get the 3D distance data from your terrain . Once added you can use the Feature Info Tool to get 3D distances or view the data via the Attribute Editor.
It may help to visualize what GM is trying to deliver when generating your contours. The image below is from your data where I have created a 0m user contour and compared it to your gridded surface when clamped out to a maximum elevation of 0m. What GM does is generate a reasonable contour along fragmented pixel data as shown. Therefore I assume that when you confine the process to a different area the second time around, that each contour might start at different points and therefore take slightly different routes than before. Note that your pixels are 10m and that you are generating 0.5m contours with it.
You can use Analysis > Measure Volume Between Surfaces
- DTM2 is the layer to subtract from
- DTM1 is the layer to subtract
Measurements:Total Volume Between Surfaces: 9947.185 cubic metersCut Volume: 8038.4232 cubic metersCut 2D Surface Area: 4931.6 sq mCut 3D Surface Area: -Fill Volume: 1908.7617 cubic metersFill 2D Surface Area: 13809 sq mFill 3D Surface Area: -LAYER_COMPARE: DTM2.tifLAYER_BASE: DTM1.tifREPORT_TIME: 01/06/2017 12:23:07AVG_Z_DELTA: 0.327 mMAX_Z_DELTA: 5.345 mMIN_Z_DELTA: -1.599 m
- Make sure you have assigned the elevations first then (Vertex Editing > Edit Feature Vertices)
- Select the lines
- 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:
- Right-click the raster layer
- Create Area Features from Equal Values in Selected Layer
- Choose Only Create Areas for Selected Colors and enter the RGB value of your contour e.g. 0,0,0 for black
- Select the newly created area features
- Right-click > Move/Reshape Feature(s) > SIMPLIFY
- Right-click > Move/Reshape Feature(s) > SMOOTH
- Right-click > Advanced Feature Creation Options > Create Area Skeletons/Center Lines
- Join any gaps in the new contour lines:
- Right-click > Crop/Combine/Split Functions > COMBINE
- 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.
I suppose a workaround would be to export to GeoTIFF with a white background and then use 'Create Area Features from Equal Values in Selected Layer' on the imported raster. Choose 'Only Create Areas for Selected Colors' and pick white. This will create polygons of the white areas. Just convert these to Line Features and delete the outer boundary and then convert back to Area Features. Now you can select a boundary to use as the Grid Bounds for the Gridding process or as a Cropping boundary (Right Click Layer > Options > Cropping).
The whole thing took around 2 minutes on your image: