Changes between Version 18 and Version 19 of Help/LeicaLidarDems


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Timestamp:
May 19, 2009 3:32:13 PM (10 years ago)
Author:
mark1
Comment:

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  • Help/LeicaLidarDems

    v18 v19  
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    62 Assuming that there are only small holes in the data set and the DEM is required only within the lidar swath coverage, we can use the `r.surf.idw` command to interpolate over the lidar. This command will also interpolate into the GRASS region where the LIDAR is undefined.
     62Assuming that there are only small holes in the data set and the DEM is required only within the lidar swath coverage, we can use the `r.surf.idw` command to interpolate over the lidar. But because this command only gives integer results, we multiply by 100 first and then divide by 100 afterwards, to try and maintain some precision. This command will also interpolate into the GRASS region where the LIDAR is undefined.
    6363
    64 6. '''`r.surf.idw input=lidar_mosaic output=lidar_mosaic_idw`'''
     646.
     65'''`r.mapcalculator amap=lidar_mosaic formula=100*A outfile=lidar_mosaicx100 help=-`'''
     66
     67'''`r.surf.idw input=lidar_mosaicx100 output=lidar_mosaic_idwx100`'''
     68
     69'''`r.mapcalculator amap=lidar_mosaic_idwx100 formula=0.01*A outfile=lidar_mosaic_idw help=-`'''
    6570
    6671where the output raster, lidar_mosaic_idw, has been interpolated using an inverse distance weighted formula. As well as filling in holes within the lidar swath, this will also interpolate over empty parts of the GRASS region, resulting in possibly unrealistic data values.
     
    79847. '''`r.mask input=<maskmapname>`'''
    8085
    81 and perform the interpolation step:
     86and perform the interpolation step (with precision maintaining commands before and after as above):
    8287
    83 8. '''`r.surf.idw input=lidar_mosaic output=lidar_mosaic_idw`'''
     888.
     89'''`r.mapcalculator amap=lidar_mosaic formula=100*A outfile=lidar_mosaicx100 help=-`'''
     90
     91'''`r.surf.idw input=lidar_mosaicx100 output=lidar_mosaic_idwx100`'''
     92
     93'''`r.mapcalculator amap=lidar_mosaic_idwx100 formula=0.01*A outfile=lidar_mosaic_idw help=-`'''
    8494
    8595this results in a map where the internal holes have been filled, but the area outside the swath coverage remains unchanged.
     
    105115}}}
    106116
     117To output the DEM:
     118
     11911.    '''`r.out.gdal input=<DEMmapname> type=Int16 output=<outputDEMfile>`'''
    107120------------
    108121== Making the DEM suitable for azgcorr ==