GENERATE_ELEV_GRID - Different results from script command and manual grid generating

michal

Hello.

I am pretty new in Global Mapper. I have an issue with grid generated from LAS data. If I use the command in user interface, the GMG result is ok, if I use the script command the elevation values in GMG are rounded to whole meters. See my screenshots below. Is there a way how to specify same behavior of the script as in the user interface command?

Thank you for help.

Michal Becicka

michal

Here is also the loop in my script which generates GMGs:

DIR_LOOP_START DIRECTORY="%UTM_Tiles_Dir%shp_export\tiles\" FILENAME_MASKS="*.shp"

     DEFINE_VAR NAME="Tile" VALUE="%FNAME_W_DIR%" TYPE="SHAPEFILE"
     IMPORT FILENAME="%Tile%"

     EXPORT_VECTOR FILENAME="%UTM_Tiles_Dir%shp_export\points\UTM_Tilename.shp" EXPORT_LAYER="%UTM_Tiles_Dir%shp_export\points\UTM_Points.shp" LAYER_BOUNDS="%Tile%" \
 TYPE=SHAPEFILE SHAPE_TYPE=POINTS GEN_PRJ_FILE=YES OVERWRITE_EXISTING=YES
     IMPORT FILENAME="%UTM_Tiles_Dir%shp_export\points\UTM_Tilename.shp"

     DEFINE_VAR NAME="UTM_Tile" VALUE_ATTR="<Feature Name>" FILENAME="%UTM_Tiles_Dir%shp_export\points\UTM_Tilename.shp"

     //*Use of the Resolution*
     GENERATE_ELEV_GRID ELEV_UNITS=METERS SPATIAL_RES_METERS=2.0 LAYER_BOUNDS="%Tile%" LAYER_BOUNDS_EXPAND="200" LAYER_DESC="Temp_Grid"

     //*Use of the Result Name*
     EXPORT_ELEVATION FILENAME="%GMG_Directory%las2gmg_output\Ground_2M_Grid_0%UTM_Tile%.GMG" TYPE=GLOBAL_MAPPER_GRID ELEV_UNITS=METERS

     UNLOAD_LAYER FILENAME="%Tile%"
     UNLOAD_LAYER FILENAME="Temp_Grid"
     UNLOAD_LAYER FILENAME="%UTM_Tiles_Dir%shp_export\points\UTM_Tilename.shp"

DIR_LOOP_END

bmg_bob

Hello,

The Global Mapper Grid format stores elevation values as whole numbers, not fractional numbers, so you should use ELEV_UNITS=CENTIMETERS (or MILLIMETERS, if you need more precision) instead of METERS.

Cheers,

Bob

michal

Thank you for the answer.

I was trying to use centimeters before but the result was 100x lower elevation than it should be (see the screenshot - the elevation should be from 550m to 850m not 5.5m to 8.5m). I thought I can't use the centimeters because the script loads the LAS data which are in meters and assumes that these numbers are centimeters. What I am thinking wrong about?

Michal

michal

I was playing with units and Bob is right. I just had to delete units in the command GENERATE_ELEV_GRID so now it works:

GENERATE_ELEV_GRID SPATIAL_RES_METERS=2.0 LAYER_BOUNDS="%Tile%" LAYER_DESC="Temp_Grid"

EXPORT_ELEVATION FILENAME="%My_grid%" TYPE=GLOBAL_MAPPER_GRID ELEV_UNITS=CENTIMETER

Thank you.

Michal