Google Earth 圖片處理

從Google Earth上抓回來的地圖是4326座標系的，JPEG 圖片，沒有壓縮的，質量比較好。但是相應的.map文件的格式如下：

!table
OziExplorer Map Data File Version 2.2
tianhe1.jpg
C:\users\Gecapture\tianhe1.jpg
1 ,Map Code,
WGS 84,WGS 84, 0.0000, 0.0000,WGS 84
Reserved 1
Reserved 2
Magnetic Variation,,,E
Map Projection,Latitude/Longitude,PolyCal,No,AutoCalOnly,No,BSBUseWPX,No
Point01,xy,284,197,in, deg, 23, 9.028140,N, 113, 17.976480,E, grid, , , ,
Point02,xy,8520,1970,in, deg, 23, 8.072580,N, 113, 22.894800,E, grid, , , ,
Point03,xy,8520,4334,in, deg, 23, 6.799800,N, 113, 22.885200,E, grid, , , ,
Point04,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point05,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point06,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point07,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point08,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point09,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point10,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point11,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point12,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point13,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point14,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point15,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point16,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point17,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point18,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point19,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point20,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point21,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point22,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point23,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point24,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point25,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point26,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point27,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point28,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point29,xy, , ,in, deg, , ,, , ,, grid, , , ,
Point30,xy, , ,in, deg, , ,, , ,, grid, , , ,
Projection Setup,,,,,,,,,,
Map Feature = MF ; Map Comment = MC These follow if they exist
Track File = TF These follow if they exist
Moving Map Parameters = MM? These follow if they exist
MM0,Yes
MMPNUM,4
MMPXY,1,0,0
MMPXY,2,9088,0
MMPXY,3,9088,7092
MMPXY,4,0,7092
MMPLL,1, 113.296784, 23.152230
MMPLL,2, 113.387115, 23.152230
MMPLL,3, 113.387115, 23.088601
MMPLL,4, 113.296784, 23.088601
MM1B,1.017826
LL Grid Setup
LLGRID,No,No Grid,Yes,255,16711680,0,No Labels,0,16777215,7,1,Yes,x
Other Grid Setup
GRGRID,No,No Grid,Yes,255,16711680,No Labels,0,16777215,8,1,Yes,No,No,x
MOP,Map Open Position,0,0
IWH,Map Image Width/Height,9088,7092


需要修改成爲後綴爲.tab的文件才能轉換。

!table
!version 300
!charset WindowsSimpChinese

Definition Table
File "tianhe1.jpg"
Type "RASTER"
(113.296784, 23.152230) (0,0) Label "Pt 1",
(113.387115, 23.152230) (9088,0) Label "Pt 2",
(113.296784, 23.088601) (0,7092) Label "Pt 3"
CoordSys Earth Projection 1, 104
Units "degree"

=== set_tab.rb=====
k = 0
File.open(ARGV[0], 'r').each_line do |line|
k = k+1
$filename = line.chomp if k == 2
if line[0..6] == 'MMPXY,3'
ss = line.chomp.split(',')
$width = ss[2]
$height = ss[3]
end

if line[0..6] == 'MMPLL,1'
ss = line.chomp.split(',')
$x0, $y0 = ss[2], ss[3]
end

if line[0..6] == 'MMPLL,3'
ss = line.chomp.split(',')
$x1, $y1 = ss[2], ss[3]
end
end

puts '!version 300'
puts '!charset WindowsSimpChinese'
puts
puts 'Definition Table'
puts " File \"#{$filename}\""
puts " Type \"RASTER\""
puts " (#{$x0},#{$y0}) (0,0) Label \"Pt 1\","
puts " (#{$x1},#{$y0}) (#{$width},0) Label \"Pt 2\","
puts " (#{$x0},#{$y1}) (0,#{$height}) Label \"Pt 3\""
puts ' CoordSys Earth Projection 1, 104'
puts ' Units "degree"'

=== end of ruby script ====

運行：liujun$ ruby set_tab.rb tianhe1.map

!version 300
!charset WindowsSimpChinese

Definition Table
File "tianhe1.jpg"
Type "RASTER"
( 113.296784, 23.152230) (0,0) Label "Pt 1",
( 113.387115, 23.152230) (9088,0) Label "Pt 2",
( 113.296784, 23.088601) (0,7092) Label "Pt 3"
CoordSys Earth Projection 1, 104
Units "degree"

重新定向到 ruby set_tab.rb tianhe1.map > tianhe1.tab

.tab文件準備好之後，就可以用gdalwarp 把座標系和ERSI的信息加進去生成GeoTiff 圖片了。


liujun$ gdalwarp -s_srs EPSG:4326 -of GTiff tianhe1.jpg tt.tif
Creating output file that is 9424P x 6639L.
Processing input file tianhe1.jpg.
0...10...20...30...40...50...60...70...80...90...100 - done.

然後用
liujun$ gdalinfo tt.tif
Driver: GTiff/GeoTIFF
Files: tt.tif
Size is 9424, 6639
Coordinate System is:
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.2572235630016,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4326"]]
Origin = (113.296784000000031,23.152230000000014)
Pixel Size = (0.000009584844494,-0.000009584844494)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left ( 113.2967840, 23.1522300) (113d17'48.42"E, 23d 9'8.03"N)
Lower Left ( 113.2967840, 23.0885962) (113d17'48.42"E, 23d 5'18.95"N)
Upper Right ( 113.3871116, 23.1522300) (113d23'13.60"E, 23d 9'8.03"N)
Lower Right ( 113.3871116, 23.0885962) (113d23'13.60"E, 23d 5'18.95"N)
Center ( 113.3419478, 23.1204131) (113d20'31.01"E, 23d 7'13.49"N)
Band 1 Block=9424x1 Type=Byte, ColorInterp=Red
Band 2 Block=9424x1 Type=Byte, ColorInterp=Green
Band 3 Block=9424x1 Type=Byte, ColorInterp=Blue


然後就可以用 gdal2tiles.py 來生成cahce文件了。由於邊界問題，所以還不是特別規整，這個可以嘗試。

liu-juns-macbook-pro:Gecapture liujun$ gdal2tiles.py tt.tif ./tt_out/
Generating Base Tiles:
0...10...20...30...40...50...60...70...80...90...100 - done.
Generating Overview Tiles:
0...10...20...30...40...50...60...70...80...90...100 - done.

1km的高度，就是17級的。

如果要18， 19甚至更高級別的圖片就需要重新下載更詳細的Google圖片


如果要加到OpenLayers 裏面，可以先在geoserver裏面登記一下，然後再用相同的方法處理一下。