Changes between Version 16 and Version 17 of Processing/SRTMDEMs


Ignore:
Timestamp:
Oct 21, 2010 2:57:58 PM (9 years ago)
Author:
anch
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • Processing/SRTMDEMs

    v16 v17  
    2525For ASTER data:
    2626{{{
    27 r.in.gdal input=<aster_tile>_dem.tif output=aster_data
     27r.in.gdal input=<aster_tile>_dem.tif output=<MAP_NAME>
    2828}}}
    2929For SRTM data:
    3030{{{
    31 r.in.gdal input=w001001.adf output=srtm_data
     31r.in.gdal input=w001001.adf output=<MAP_NAME>
    3232}}}
    3333
     
    3636If the data you have downloaded spans multiple tiles, then you will need to run the above but inside a for loop like so:
    3737
     38For ASTER data:
    3839{{{
    3940for tile in `ls *_dem.tif`;
    4041do r.in.gdal input=$tile output=$tile.tile;
     42done
     43}}}
     44For SRTM data:
     45{{{
     46for tile in `ls *.adf`;
     47r.in.gdal input=$tile output=$tile.tile;
    4148done
    4249}}}
     
    5663}}}
    5764
    58 I will refer to the comma separated list after "rast=" as TILELIST from hereon - This is the bit you need.
     65I will refer to the comma separated list after "rast=" as <TILELIST> from hereon - This is the bit you need.
    5966
    6067Now run
    6168{{{
    62 g.region rast=TILELIST
     69g.region rast=<TILELIST>
    6370}}}
    6471
     
    6673
    6774{{{
    68 r.patch input=TILELIST output=some_name
     75r.patch input=<TILELIST> output=<MAP_NAME>
    6976}}}
    7077
    71 Write down some_name somewhere - you will need it in a minute.
     78Write down <MAP_NAME> somewhere - you will need it in a minute.
    7279
    73805. Quit Grass and then start it up again. Select a location using UTM projection for the target area or create one if none is available - make sure you've got the right UTM zone. Note you can also use whatever other projection you want, but this guide assumes you want UTM.
     
    7582Check [http://www.gpsinformation.org/utm-zones.gif] For the UTM zone
    7683
    77 6. Use a conversion utility (eg see the spreadsheet at [http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM#Spreadsheet http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM#Spreadsheet]) to determine the boundaries of the target flight in meters within the selected UTM zone. If the flight spans two or more UTM zones, you will have to calculate the offsets appropriate to work out the east and west boundaries of the area. eg. If western boundary is zone 32 and eastern boundary is zone 33, for eastern value use zone 32, add 750000 to value from spreadsheet
    78 to find eastings relative to zone 32 bound.
     846. Here we can use the manual method of calculating the eastings/northings or simply grab them from the tile(s) we have input.
    7985
    80 6-alternative.  Once all of the
     86'''Manual:'''
     87Use a conversion utility (eg see the spreadsheet at [http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM#Spreadsheet http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM#Spreadsheet]) to determine the boundaries of the target flight in meters within the selected UTM zone. If the flight spans two or more UTM zones, you will have to calculate the offsets appropriate to work out the east and west boundaries of the area. eg. If western boundary is zone 32 and eastern boundary is zone 33, for eastern value use zone 32, add 750000 to value from spreadsheet to find eastings relative to zone 32 bound.
    8188
    82 7. Set active region to calculated eastings/northings using:
     897. Set active region to calculated eastings/northings using
     90
    8391{{{
    8492g.region n=<north val> s=<south val> e=<east val> w=<west val> res=50
    8593}}}
    8694
     95For ASTER please put res=30
     96
    87978. Use r.proj to convert from lat/long to UTM:
    8898{{{
    89 r.proj input=<input_map_name> location=<lat/long_location> mapset=<lat/long_mapset> output=<output_map_name>
     99r.proj input=<MAP_NAME> location=<lat/long_location> mapset=<lat/long_mapset> output=<output_map_name>
    90100}}}
     101
     102Where <MAP_NAME> is what we created in step 4.
    91103
    921049. If r.proj gives an error saying that the input map is outside the bounds of the current region, go back to step 6 and check your numbers
    93105
     106
     107'''Other method:'''
     108Set the northings/eastings to something very large e.g.
     109
     110{{{
     111g.region n=50000000 s=0 e=50000000 w=-50000000 res=50
     112}}}
     113
     114For ASTER please put res=30
     115
     1168. Use r.proj to convert from lat/long to UTM:
     117{{{
     118r.proj input=<MAP_NAME> location=<lat/long_location> mapset=<lat/long_mapset> output=<output_map_name>
     119}}}
     120
     121Where <MAP_NAME> is what we created in step 4.
     122
     1239.
     124
     125Set the new region
     126
     127{{{
     128g.region rast=<output_map_name>
     129}}}
     130
     131You can run
     132
     133{{{
     134gis.m &
     135}}}
     136
     137To run a GUI and check whether the DEM covers the correct area, or to make the area smaller.
     138
    9413910 Output ASCII DEM from converted map as normal (see [wiki:Processing/NextMapDEMs Creation of DEMs from NextMap data])
    95140