[GRASS-dev] Projection-problem

[Stephan Holl]

Hello Paul,

On Thu, 11 May 2006 12:35:46 +0100 (BST) Paul Kelly
<paul-grass at stjohnspoint.co.uk> wrote:

> Hello Stephan
> 
> On Thu, 11 May 2006, Stephan Holl wrote:
> 
> > But, it does not import any other projected dataset anymore unless I
> > specify -o which mostly is unintended for projected data.
> >
> [...]
> > # Reimporting
> > v.in.ogr dsn=/tmp layer=spear_roads out=test2222
> > ERROR: Projection of dataset does not appear to match current
> > location.
> >
> >       LOCATION PROJ_INFO is:
> >       name: UTM
> >       datum: nad27
> >       nadgrids: conus
> >       proj: utm
> >       ellps: clark66
> >       a: 6378206.4000000004
> >       es: 0.0067686580
> >       f: 294.9786982000
> >       zone: 13
> >
> >       cellhd.proj = 0 (unreferenced/unknown)
> >                   ^^^^^^^^^ Wrong!
> 
> Hmm I don't see how the change I made could affect that at all. 

I don`t understand this at all! 

> What
> does g.region -p
> say?

Thats what it says...
g.region -p
projection: 1 (UTM)
zone:       13
datum:      nad27
ellipsoid:  clark66
north:      4928010
south:      4913700
west:       589980
east:       609000
nsres:      30
ewres:      30
rows:       477
cols:       634

Strange. Everything should be right.

> 
> I should also say that the projection comparison code is "just
> there", I don't like it, don't think it is a good way of testing
> things nor very robust/comprehensive, but there is no better way of
> doing it so it stays there!

Yes, no problem at all.

Ahhh, I found out:

# show layers in folders
v.in.ogr -l dsn=/tmp layer=spear_roads out=test5
Data source contains 3 layers:
spear_roads, flst_gef, NSG_Beispie
^^^          ^^^        ^^^
EPSG:26713 EPSG:31467 EPSG:31467


# now import
v.in.ogr dsn=/tmp layer=spear_roads out=test5
ERROR: Projection of dataset does not appear to match current location.

       LOCATION PROJ_INFO is:
       name: UTM
       datum: nad27
       nadgrids: conus
       proj: utm
       ellps: clark66
       a: 6378206.4000000004
       es: 0.0067686580
       f: 294.9786982000
       zone: 13

       cellhd.proj = 0 (unreferenced/unknown)

# different syntax
v.in.ogr dsn=/tmp/spear_roads.shp out=test5

A datum name nad27 (North_American_Datum_1927) was specified without
transformation parameters. WARNING: Non-interactive mode: the GRASS
default for nad27 is towgs84=-22.000,157.000,176.000.
Projection of input dataset and current location appear to match.
Proceeding with import...
[successfull import]

The first syntax fails, if the datasource (the folders the shapes are
in) shapefiles with different projections reside in.

No problem, if you export heaps of spearfish-shapes, but put another
shape with e.g. EPSG:4326 inside and you will fail to import the
dataset with the second syntax.

This seems to be a bug (if anybody can confirm of course)

Best
	Stephan


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