[gdal-dev] Help with GeoData
barry at pocket-link.com
Sat Aug 23 14:57:03 EDT 2008
I am very new to geo data and need some help.
I will try and explain what I have and where I need to get to. I have
developed some custom software that reads in Google Map files. These are
organised in layers 0 - 20 with each image being a jpg file. Each file is
256 x 256 pipels in size. This software works OK at the moment. The data
that I am using is downloaded from google maps as I have only needed small
test datasets up until now.
I have purchased a data set of Portugal which I have in 2 Formats (Mapinfo
and Arcview), I have choosen to use the Mapinfo data set. This has 8 Layers.
and is split into much larger tiles. i.e 6000ish by 6000ish pixels.
In short I need to convert all the mapinfo data to a google style dataset so
that the existing software can use it. I would also like to (if possible use
Mapserver to serve the new data so that I can store only the bits I need off
Where I am now.
I have downloaded and installed GDAL and FWTools.
using gdalinfo and ogrinfo for both data sets as well as google searches
I think that the google data uses the wsg84 datum in mercator projection.
(This does not mean a lot to me but I have read up as much as I can)
I think the Mapinfo data uses the wsg84 datum and a Lambert Conical
the Mpainfo tab file is:
(0,0) (0,2304) Label "Pt 1",
(0,7558272) (0,0) Label "Pt 2",
(7558272,7558272) (2304,0) Label "Pt 3",
(7558272,0) (2304,2304) Label "Pt 4"
CoordSys Earth Projection 3, 104, "m", 5, 49.08516574, 44, 54, 1507373,
And using gdalinfo i get the following:
Size is 2304, 2304
Coordinate System is `'
Origin = (0.000000000000000,7558272.000000000000000)
Pixel Size = (3280.500000000000000,-3280.500000000000000)
Image Structure Metadata:
Upper Left ( 0.000, 7558272.000)
Lower Left ( 0.0000000, 0.0000000)
Upper Right ( 7558272.000, 7558272.000)
Lower Right ( 7558272.000, 0.000)
Center ( 3779136.000, 3779136.000)
Band 1 Block=2304x8 Type=Byte, ColorInterp=Palette
Image Structure Metadata:
Color Table (RGB with 16 entries)
I have uploaded the tif file if it helps!
I have played with cs2cs to try and change the projection so that it would
be the same a s the google one(I dont even know if I need to do this, but
If I under stand the above correctly the tif is 2304 pixels wide and each
pixel represents 3280.5 meters wide, so this tif represents a total size in
metrs of 7558272 wide, as can be seen in the top left size etc. But where is
this referenced from? I think I need to make sure that booth the google data
and mapinfo data are referenced from the same place.
Can any one please tell me the best way to try and acheive this?
A breakdown of steps would be great, and a confirmation of my understading
so far would also help.
Many thanks in advance.
View this message in context: http://n2.nabble.com/Help-with-GeoData-tp778740p778740.html
Sent from the GDAL - Dev mailing list archive at Nabble.com.
More information about the gdal-dev