[GRASS-user] Re: Import/conversion problem

Adam Dershowitz, Ph.D., P.E. adershowitz at exponent.com
Fri Feb 11 17:40:07 EST 2011

On Feb 11, 2011, at 9:23 AM, Adam Dershowitz, Ph.D., P.E. wrote:

> I am trying to import some data in GRASS and have run into a problem.  I hope someone can give me a little insight to help out.
> 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

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

I found this link:

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

Then it imports into grass fine.  So, it seems like something is broken with that projection.


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