[GRASSLIST:2420] Re: v.proj problems

[Glynn Clements]

Ian Macmillan wrote:

> > The values for north and south in the utm location should both be 
> > positive. I tried
> > 
> > north:      8112600
> > south:      3770400
> > 
> > and got Chile nicely in the monitor window.
> > 
> > rgds
> > Morten
> >  
> Hmm, that is interesting, then I guess the problem isn't with v.proj.  It is
> with r.in.gdal.  I imported a bunch of landsat rasters (from university of
> maryland).  The utm region that I gave is the region that shows when I set
> g.region raster=mylandsat.  I have posted the meta file here for the geotiffs i
> imported.
> 
> www.uweb.ucsb.edu/~ian_macmillan/p233r084_7x19991226.txt

GROUP = METADATA_FILE
		...
		SCENE_UL_CORNER_MAPX = 232531.500
		SCENE_UL_CORNER_MAPY = -3727258.500
		SCENE_UR_CORNER_MAPX = 415957.500 
		SCENE_UR_CORNER_MAPY = -3755644.500
		SCENE_LL_CORNER_MAPX = 194484.000
		SCENE_LL_CORNER_MAPY = -3906609.000
		SCENE_LR_CORNER_MAPX = 378223.500
		SCENE_LR_CORNER_MAPY = -3934966.500
		...
		GROUP = PROJECTION_PARAMETERS 
			...
			FALSE_NORTHING = 0      
			...
			MAP_PROJECTION = "UTM"
		END_GROUP = PROJECTION_PARAMETERS 
		GROUP = UTM_PARAMETERS 
			ZONE_NUMBER = +19

This indicates that it is using a northern-hemisphere UTM zone for
southern-hemisphere data. Some software may cope with it, but I
wouldn't rely upon it. In particular, "south: defined" will completely
mess things up (the data *should* be using a southern-hemisphere zone,
but it isn't).

-- 
Glynn Clements <glynn.clements at virgin.net>