Changes between Version 2 and Version 3 of Processing/LIDARDEMs


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Timestamp:
Apr 9, 2008 11:00:17 AM (11 years ago)
Author:
benj
Comment:

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  • Processing/LIDARDEMs

    v2 v3  
    4545In the given example, there are a very few values between 20-30m at the bottom end, and a big gap at the top end before a small number of values above 590m (nothing between 240m and 590m). So it would be sensible to pick 30m as a minimum cutoff and 250m as a maximum. Note that because the histogram is on a log scale the difference in numbers of points at both ends is much larger than it looks at first glance.
    4646
    47 3. Open GRASS, select (or create) an appropriate UTM/WGS84 location and set the region appropriately for the dataset - easiest way is to look at the start of the trimmed lidar data file for the starting co-ordinates of the first line, set an approximate region from there, view the map in GRASS and then adjust the region appropriately.
     473. Check the LIDAR data projection in the header file. Open GRASS, select (or create) an a location in the appropriate projection and set the region appropriately for the dataset - easiest way is to look at the start of the trimmed lidar data file for the starting co-ordinates of the first line, set an approximate region from there, view the map in GRASS and then adjust the region appropriately.
    4848
    49494. Read in the trimmed lidar file using r.in.xyz:
     
    5757}}}
    5858
    59 6. Generate an ASCII DEM as per [wiki:Processing/NextMapDEMs Creation of DEMs from NextMap data]:
     596. Reproject the dataset if necessary to match the projection of the flight data (should be the same, but conceivably won't be). See [wiki:Processing/SRTMDEMs Creation of DEMs from SRTM 90m data] for how to do this.
     60
     617. Generate an ASCII DEM as per [wiki:Processing/NextMapDEMs Creation of DEMs from NextMap data]:
    6062{{{
    6163r.out.ascii input=<lidar_interp_map> output=lidar.dem null=0