other versions
- jessie 6.4.4-1
d.out.gpsdrive(1grass) | Grass User's Manual | d.out.gpsdrive(1grass) |
NAME¶
d.out.gpsdrive - Export display monitor to a GpsDrive compatible backdrop imageKEYWORDS¶
display, export, GPSSYNOPSIS¶
d.out.gpsdriveFlags:¶
- -j
-
- --verbose
-
- --quiet
-
Parameters:¶
- output=string
-
DESCRIPTION¶
d.out.gpsdrive exports the current GRASS display monitor to a GpsDrive compatible backdrop image and updates the GpsDrive image list with the appropriate geo-referencing information. Use at your own risk. Do not use as a primary means of navigation. This software comes with absolutely no warranty.NOTES¶
Maps are saved in the user's ~/.gpsdrive/maps/ directory. Geo-referencing information is added to the user's ~/.gpsdrive/maps/map_koord.txt file. JPEG output requires the pngtopnm and pnmtojpeg programs from the NetPBM tools. GpsDrive assumes northings are not rotated compared to true-geographic north. If you are using a projection with significant curvature away from the central meridian, or a map datum with a significant rotational component, then you will likely end up with a distorted or inexact background map! Keeping the area small will lessen the error, but not eliminate it, if necessary you could reproject the map into a custom projection (such as tmerc) centered directly on the center of your map. You can check the local convergence angle (difference between grid north and true north) with "g.region -n". To avoid distortion, anything more global than 1:150k to 1:500k should come from a lat/lon location. Anything more local than that will look better coming from a projected system such as UTM. The extent of a map given a target scale can be calculated with x_ext=scale*(1280/2817.95). e.g. 1:50,000 translates to approx a 22.7km x 18.2km image window in the GIS. For your convenience (calculations are rough, but nominal):Batch export¶
It may be desirable to create a series of image tiles covering a large area. An easy way to do this is to run d.out.gpsdrive in a shell loop. Here is an example Bash script contributed by Manuel Morales:east=$(echo "scale=8; $west+$unit_ew" | bc)
for j in `seq 1 $iter`;
do
g.region n=$(echo "scale=8; $north-($j-1) * $unit_ns/2" | bc) \
s=$(echo "scale=8; $north-($j-1) * $unit_ns/2-$unit_ns" | bc ) \
w=$west e=$east ewres=$ewres nsres=$nsres
d.redraw
d.out.gpsdrive -j tile_${i}_${j}
done
shift_west=$(echo "scale=8; ($ew_extent-$unit_ew)/($panels_ew-1)" | bc)
west=$(echo "scale=8; $west+$shift_west" | bc)
SEE ALSO¶
d.info, d.grid, d.out.file, d.out.png, d.save, g.region, v.in.garminAUTHOR¶
Hamish BowmanDepartment of Marine Science
GRASS 6.4.4 |