We have just received a large set of DEMs at work and I would like to generate contours from them. The DEMs have a resolution of 1m and a size of 1kmx1km.
Output from gdalinfo:
Driver: AAIGrid/Arc/Info ASCII Grid Files: 380000_6888000_1k_1m_DEM_ESRI.asc Size is 1000, 1000 Coordinate System is `' Origin = (380000.000000000000000,6888000.000000000000000) Pixel Size = (1.000000000000000,-1.000000000000000) Corner Coordinates: Upper Left ( 380000.000, 6888000.000) Lower Left ( 380000.000, 6887000.000) Upper Right ( 381000.000, 6888000.000) Lower Right ( 381000.000, 6887000.000) Center ( 380500.000, 6887500.000) Band 1 Block=1000x1 Type=Float32, ColorInterp=Undefined NoData Value=-9999
I know I can use gdal_contour to generate the contours (my blog post on the topic) but I'm wondering what some best practices for generating contours are.
Are there any rules you should follow to get the most out of the contours but not make stuff up or loose too much information?
Say I want to generate three sets of contours:
Is there anything I should do to the DEM before each set?
Is post smoothing of the lines a good way to go or is smoothing the raster a better option?