d.out.gpsdrive(1)

1d.out.gpsdrive(1)             Grass User's Manual            d.out.gpsdrive(1)
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NAME

6       d.out.gpsdrive  - Export display monitor to a GpsDrive compatible back‐
7       drop image
8

KEYWORDS

10       display, export, GPS
11

SYNOPSIS

13       d.out.gpsdrive
14       d.out.gpsdrive help
15       d.out.gpsdrive [-j] output=string
16
17   Flags:
18       -j  Make JPEG instead of PNG image
19
20   Parameters:
21       output=string
22           name for new map image (lives in ~/.gpsdrive)
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DESCRIPTION

25       d.out.gpsdrive exports the current GRASS display monitor to a  GpsDrive
26       compatible  backdrop image and updates the GpsDrive image list with the
27       appropriate geo-referencing information.
28
29       Use at your own risk. Do not use as  a  primary  means  of  navigation.
30       This software comes with absolutely no warranty.
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NOTES

33       Maps  are  saved  in  the user's ~/.gpsdrive directory. Geo-referencing
34       information is added to the user's ~/.gpsdrive/map_koord.txt file.
35
36       JPEG output requires the  pngtopnm  and  pnmtojpeg  programs  from  the
37       NetPBM tools.
38
39       GpsDrive  assumes northings are not rotated compared to true-geographic
40       north.  If you are using a projection with significant  curvature  away
41       from the central meridian, or a map datum with a significant rotational
42       component, then you will likely end up  with  a  distorted  or  inexact
43       background  map!  Keeping the area small will lessen the error, but not
44       eliminate it.
45
46       Best output is created from a Lat/Lon location or by keeping the output
47       area  small  (1:50,000).  This  translates  to approx a 22.7km x 18.2km
48       image window in the GIS. [x_ext=scale*(1280/2817.95)]
49
50       For your convenience (calculations are rough, but nominal):
51       1:50,000 uses a region 22.7km x 18.2km.
52       1:75,000 uses a region 34.1km x 27.3km.
53       1:100,000 uses a region  45.4km x 36.3km.
54       1:175,000 uses a region  79.5km x 63.6km.
55
56       Maps exported from lat-lon locations will be  given  a  "top_"  prefix.
57       Maps  exported  from  locations  of  other  projections will be given a
58       "map_" prefix. This is done so GpsDrive knows how to  scale  the  image
59       correctly.
60
61       GpsDrive requires backdrop images to be 1280x1024 pixels in size. While
62       this script takes care of that automatically, to avoid  annoying  bands
63       on  the sides of your image you may want to set up your display monitor
64       at half-scale (same aspect ratio) and use d.zoom  to  select  the  full
65       frame. For example:
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67
68       export GRASS_WIDTH=640
69       export GRASS_HEIGHT=512
70       d.mon x0
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72       Map  scaling  is  set from the region settings so should work correctly
73       even when the display's aspect ratio does not match that of the  output
74       image.
75
76   Batch export
77       It  may be desirable to create a series of image tiles covering a large
78       area.  An easy way to do this is to run d.out.gpsdrive in a shell loop.
79       Here is an example Bash script contributed by Manuel Morales:
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81
82       #!/bin/bash
83       # map scale is determined by "panels" by dividing the N-S
84       # region extent into that number of maps. Note that the
85       # generated maps overlap by 1/2 along the N-S axis and by
86       # approximately 1/2 along the E-W axis.
87       panels=3
88       iter=$((panels*2-1))
89       eval `g.region -eg`
90       eval `g.region -g`
91       north=$n
92       south=$s
93       west=$w
94       east=$e
95       unit_ns=$(echo "scale=8; $ns_extent / $panels" | bc)
96       unit_ew=$(echo "scale=8; $unit_ns * 4/3" | bc)
97       panels_ew=$(echo "((2*$ew_extent / $unit_ew +.5 ) -1) / 1" | bc)
98       for i in `seq 1 $panels_ew`;
99       do
100         east=$(echo "scale=8; $west+$unit_ew" | bc)
101         for j in `seq 1 $iter`;
102           do
103           g.region  n=$(echo  "scale=8;  $north-($j-1)  *  $unit_ns/2"  | bc)
104       \
105               s=$(echo "scale=8; $north-($j-1) * $unit_ns/2-$unit_ns" | bc  )
106       \
107               w=$west e=$east ewres=$ewres nsres=$nsres
108               d.redraw
109               d.out.gpsdrive -j tile_${i}_${j}
110           done
111         shift_west=$(echo  "scale=8;  ($ew_extent-$unit_ew)/($panels_ew-1)" |
112       bc)
113         west=$(echo "scale=8; $west+$shift_west" | bc)
114       done
115
116       Note that to get a  smoother  transition  between  backdrop  maps  this
117       script creates overlapping tiles.
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AUTHOR

126       Hamish Bowman
127
128       Department of Marine Science
129       University of Otago
130       New Zealand
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132       Last changed: $Date: 2007/03/08 13:51:30 $
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134       Full index
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138GRASS 6.2.2                                                  d.out.gpsdrive(1)

NAME

KEYWORDS

SYNOPSIS

DESCRIPTION

NOTES

SEE ALSO

AUTHOR