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Forkboy2

Freeware to reproject state plane raster data?

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I have some good photo imagery, but it is projected into the state plane coordinate system Hawaii zone 3 (Oahu). ERDAS viewfinder doesn't seem to recognize this projection, that is the only software I have for reprojecting rasters. I have one file that's in MrSID. I saved it in tiff and it ended up over 4 gigabytes! So I got some alternative files (not mosaic'ed) that are in jpg with world files.I used a conversion program (corpscon) to convert the UL corner coordinates from the original (old hawaii datum using Clarke ellipsoid and state plane zone 3) into UTM zone 4/ meters and NAD83.Hawaii state plane zone 3 uses a transverse mercator projection, but the projection parameters aren't the same as for a UTM (at least, I don't think they are).I used fGIS to find the LR point, converted it and used that to compute a new world file based on UTM NAD83 (assuming that what I did has any validity).I took a look at the new registration against some vector data, and it appears to "mostly" register correctly (I don't know what the accuracy of the vector data is so I don't really have "ground truth").I'm thinking of converting a file to bmp and trying Luis' reproject function in sbuilder to get the file into geo coordinates, unless some one can give me a better option. scott s..

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>I'm thinking of converting a file to bmp and trying Luis'>reproject function in sbuilder to get the file into geo>coordinates, unless some one can give me a better option. Hi,You need to convert from Transverse Mercator with the following parameters:Datum = NAD83 (SBuilder has this datum)Central Longitude = 158WCentral Latitude = 21N 10'False East = 500000False North = 0I can not say which Scale Factor to use!You also need to figure out the borders of the bitmap.Regards, Luis

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Hi Scott,Here I am again ... Just made a search and found:http://gpsinformation.net/mapinfow-e.xlswhere I could see the scale factor for your data = 0.99999Note that Sbuilder assumes meters as the unit of distance. For raster bitmap file reprojection this is of limited importance. You specify the False North parameter in meters and the borders should be converted to meters before entered in the bitmap sister TXT file.If you are converting a vector BLN file, you need to convert all the coordinates pairs of the BLN file from feet to meters (Excel?)Regards, LuisPS: I would be very intersted to know what you get if you are going to try SBuilder for this task.

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Thanks Luis,I actually had found (this weekend) the transverse mercator data from a .prj file that accompanies some shapefiles that I already reprojected in fGIS, which does a great job for this. I also have to convert the datum from "Old Hawaiian" but I also have the required data for the Clarke spheriod, so that much is OK.For sbuilder, I first have to figure out a way to convert the jpg into 24 bit bmps, which I will do if I can't get any GIS software that does it right from jpg, or tiff.scott s..

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Hi Scott,I will be grateful if you have any chance of confirming that the reprojection function in SBuilder works as expected. I only have a confirmation from Arno and would like to know if it works in different contexts.Regarding JPEG versus 24-bit bitmap, I think that, either before or after the reprojection, you need to switch to the bitmap format. I assume that you aim at photo scenery and that the resample only accepts bitmaps.You said before that you have a 4 GB Tiff image. If that is uncompressed, it should be about 36,000 x 36,000 pixels. In that case case it will take a lot of time in SBuilder. In my Pentium 4 at 2.4GHz a 5,000 x 5,000 bitmap takes about 2 or 3 minutes to convert.Regards, Luis

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I tested with a 4050x4050 pixels aerial photo. On my AMD 2500+ I think it also took around 2 minutes. So with larger images you certainly need some patience :).Luis, I think I should have some other photos laying around. I will give them a test as well.

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After a lot of googling and playing around, I think my problem is that the MrSID photo file I have doesn't have any projection data on it, that's why I can't reproject it as - is. But it appears that any possible fix is still going to require translating the .sid into .tif, and it seems like file size is just going to explode. So I am pretty much resigned to d/ling the un-mosaiced .jpg files and working them individually (or maybe trying bigjpeg on them).scott s..

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Hi Scott,yup, those MrSid wavelet-coded images sure unpack to something gigantonormous ;-)At the LizardTech website there are a couple of tools that might help you. MrSidInfo reads image information embedded in MrSid files, MrSID Decode turns them into tiffs (with the additional option of scaling the output, e.g., 1/4 of the original size), and MrSID SDW writes a world file similar to the georeferencing files that come with geotiff or geojpg.http://www.lizardtech.com/download/dl_options.php?page=tools Cheers, Holger

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Mind if I ask where you're downloading the aerials from? Is there a free online source? I've never been able to find any decent aerials for hawaii.Matt

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I have been using two sources.1. Hawaii State GIS http://www.hawaii.gov/dbedt/gis/download.htmThis has LANDSAT image not really good enough for texturing. These files are projected to UTM zone 4 and NAD83 datum.2. C/C Honolulu GISftp://gisftp.hicentral.com/This has good photos for just downtown Honolulu and Waikiki and are the ones I am now using. The files are projected to SPCS Hawaii zone 3 (FIPS 5103) and Old Hawaiian datum.There are also scanned 24k USGS DRGs for Oahu and Maui here:http://www.soest.hawaii.edu/coasts/DataDepot/DRG.htmlSOEST also has some photos, but I haven't checked these out yet.These are also NUTM4 and NAD83.Note that the first two sites are better for shapefiles, rather than raster data.scott s..

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Thanks Holger,my plan was to check out lizardtech. I still hope to use the sid photo if possible. I got kind of side tracked downloading and playing with the jpeg pieces, which led me to looking at USAPhotoMaps.scott s..

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Thanks Scott. Good stuff. They have some great historical aerials at SOEST. If you ever need any DRGs for the other islands, I have all of them.Too bad they only have shoreline areas online. Hawaii with photo real would be amazing.Matt

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