[gdal-dev] Re: gdapwarp problem

[Adam Dershowitz, Ph.D., P.E.]

On Feb 11, 2011, at 10:20 AM, Adam Dershowitz, Ph.D., P.E. wrote:

> I am having a problem trying to use gdalwarp.  Perhaps I am just missing something, but I figured I would see if someone can help.  
> 
> I downloaded some aerial imagery from here:
> http://www.michigan.gov/dnr/0,1607,7-153-10371_14546-30211--,00.html
> 
> I want to import it into a UTM zone 17 project.  So I did the following:
> gdalwarp -t_srs '+proj=utm +zone=17 +datum=WGS84' input.sid output_utm.sid
> 
> gdapwarp responds with an error, but then continues with the conversion:
> ERROR 6: Failed to initialize PROJ.4 with `+proj=omerc +lat_0=0 +lonc=0 +alpha=0 +k=1 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs '.
> lat_0 = 0 or 90 or alpha = 90
> 0...10...20...30...40...50...60...70...80...90...100 - done.
> 
> It does complete, but the area of interest is in the range of UTM (254500,4734000) and the output of gdalwarp is around 663144,240035.  
> 
> Any suggestions for what I might be doing wrong?  
> 
> 
> If I do gdalinfo on the original file here is what I get:
> 
> 
> 


I googled around some and it looks like this is actually an issue with the Michigan projection in Proj4.  

I found this link:
http://www.osgeo.org/pipermail/mapserver-users/2006-July/018292.html

And this seems to give reasonable results, based on the above:

gdalwarp -t_srs '+proj=utm +zone=17 +datum=WGS84' -s_srs '+proj=omerc +lat_0=45.309166667 +lonc=-86.0 +alpha=337.255555556 +k=0.9996 +x_0=499839.8337 +y_0=528600.2398 +ellps=GRS80 +datum=NAD83 +units=m' oakgrove_sw.sid oakgrove_sw_utm.tifg

So, I am not really sure about the source of these numbers, but it does look pretty close.

--Adam
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