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   d.out.gpsdrive exports the current GRASS display monitor to a
   [1]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.

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   Maps are saved in the user's ~/.gpsdrive directory. Geo-referencing
   information is added to the user's ~/.gpsdrive/map_koord.txt file.

   JPEG output requires the pngtopnm and pnmtojpeg programs from the
   [2]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.

   Best output is created from a Lat/Lon location or by keeping the output
   area small (1:50,000). This translates to approx a 22.7km x 18.2km
   image window in the GIS. [x_ext=scale*(1280/2817.95)]

   For your convenience (calculations are rough, but nominal):

1:50,000 uses a region 22.7km x 18.2km.
1:75,000 uses a region 34.1km x 27.3km.
1:100,000 uses a region  45.4km x 36.3km.
1:175,000 uses a region  79.5km x 63.6km.

   Maps exported from lat-lon locations will be given a "top_" prefix.
   Maps exported from locations of other projections will be given a
   "map_" prefix. This is done so GpsDrive knows how to scale the image
   correctly.

   GpsDrive requires backdrop images to be 1280x1024 pixels in size. While
   this script takes care of that automatically, to avoid annoying bands
   on the sides of your image you may want to set up your display monitor
   at half-scale (same aspect ratio) and use d.zoom to select the full
   frame. For example:

export GRASS_WIDTH=640
export GRASS_HEIGHT=512
d.mon x0

   Map scaling is set from the region settings so should work correctly
   even when the display's aspect ratio does not match that of the output
   image.

  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:

#!/bin/bash

# map scale is determined by "panels" by dividing the N-S
# region extent into that number of maps. Note that the
# generated maps overlap by 1/2 along the N-S axis and by
# approximately 1/2 along the E-W axis.
panels=3
iter=$((panels*2-1))

eval `g.region -eg`
eval `g.region -g`
north=$n
south=$s
west=$w
east=$e

unit_ns=$(echo "scale=8; $ns_extent / $panels" | bc)
unit_ew=$(echo "scale=8; $unit_ns * 4/3" | bc)

panels_ew=$(echo "((2*$ew_extent / $unit_ew +.5 ) -1) / 1" | bc)

for i in `seq 1 $panels_ew`;
do
  east=$(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)
done

   Note that to get a smoother transition between backdrop maps this
   script creates overlapping tiles.

СÐ. ТÐÐÐÐ

   [3]d.info, [4]d.grid, [5]d.out.file, [6]d.out.png, [7]d.save,
   [8]g.region, [9]v.in.garmin
   The GRASS [10]PNG driver
   The [11]GpsDrive project
   The [12]gpsd personal GPS server project

ÐÐТÐÐ

   Hamish Bowman
   Department of Marine Science
   University of Otago
   New Zealand

   Last changed: $Date: 2007-09-25 19:12:40 -0500 (ÐÑ, 25 Ñен 2007) $

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References

   1. http://www.gpsdrive.de/
   2. http://netpbm.sourceforge.net/
   3. file://localhost/root/tmp/2/fin/d.info.html
   4. file://localhost/root/tmp/2/fin/d.grid.html
   5. file://localhost/root/tmp/2/fin/d.out.file.html
   6. file://localhost/root/tmp/2/fin/d.out.png.html
   7. file://localhost/root/tmp/2/fin/d.save.html
   8. file://localhost/root/tmp/2/fin/g.region.html
   9. file://localhost/root/tmp/2/fin/v.in.garmin.html
  10. file://localhost/root/tmp/2/fin/pngdriver.html
  11. http://www.gpsdrive.de/
  12. http://gpsd.berlios.de/