[GRASS-user] Identification of projectiopn?

GRASS GRASS user
1

Hi

I have two shape files of which I do not know the projection (and it seems that the person I got them from does not know either…). The maps are from the Keurboom nature reserve area in South Africa (http://plak.co.za/moreinfo.php?id=347) and the two shp files have the folowing bounding boxes:

In layer spatial reference system units : xMin,yMin 21340.4,-3755528.75 : xMax,yMax 34244.9,-3749187.87

In layer spatial reference system units : xMin,yMin 17001.2,-3754438.15 : xMax,yMax 37019.9,-3743929.77

I know this is a guessing game, but it must be a common projection - the map datum is very likely (almost certainly) WGS84.

Any suggestions welcome,

Rainer

–
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel : +33 - (0)9 53 10 27 44
Cell: +33 - (0)6 85 62 59 98
Fax (F): +33 - (0)9 58 10 27 44

Fax (D): +49 - (0)3 21 21 25 22 44

email: Rainer@krugs.de

Skype: RMkrug

2

That really is a guessing game, because even if someone finds the coordinates that the map could fit into, it still doesn’t mean that they’re correct. Do you have a reason to think that the datum is WGS84? I think South Africa probably uses a more accurate regional datum for local maps - that makes a lot more sense unless you’re working directly with web mapping applications or you want to use GPS data directly.

Isn’t there any metadata provided with the shapefiles? I didn’t know that it was possible to have a shapefile without any kind of spatial reference stored in the metadata. You could try making a location based on the shapefile as a georeferenced file.

Best,
Daniel

–
B.Sc. Daniel Lee
Geschäftsführung für Forschung und Entwicklung
ISIS - International Solar Information Solutions

Deutschhausstr. 10
35037 Marburg
Festnetz: +49 6421 379 6256
Mobil: +49 176 6127 7269
E-Mail: Lee@isi-solutions.org
Web: http://www.isi-solutions.org

Am 05.07.2011 12:59 schrieb “Rainer M Krug” <r.m.krug@gmail.com>:

Hi

I have two shape files of which I do not know the projection (and it seems
that the person I got them from does not know either…). The maps are from
the Keurboom nature reserve area in South Africa (
http://plak.co.za/moreinfo.php?id=347) and the two shp files have the
folowing bounding boxes:

In layer spatial reference system units : xMin,yMin 21340.4,-3755528.75 :
xMax,yMax 34244.9,-3749187.87

In layer spatial reference system units : xMin,yMin 17001.2,-3754438.15 :
xMax,yMax 37019.9,-3743929.77

I know this is a guessing game, but it must be a common projection - the map
datum is very likely (almost certainly) WGS84.

Any suggestions welcome,

Rainer

–
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel : +33 - (0)9 53 10 27 44
Cell: +33 - (0)6 85 62 59 98
Fax (F): +33 - (0)9 58 10 27 44

Fax (D): +49 - (0)3 21 21 25 22 44

email: Rainer@krugs.de

Skype: RMkrug

3

On Tue, Jul 5, 2011 at 1:05 PM, Daniel Lee <lee@isi-solutions.org> wrote:

That really is a guessing game, because even if someone finds the coordinates that the map could fit into, it still doesn’t mean that they’re correct. Do you have a reason to think that the datum is WGS84? I think South Africa probably uses a more accurate regional datum for local maps - that makes a lot more sense unless you’re working directly with web mapping applications or you want to use GPS data directly.

Yes - everybody is using WGS84, because it comes from a GPS - and reprojection usually is to be avoided because it is difficult to understand (I am allowed this statement - I have lived in SA and really loved it there!).

Isn’t there any metadata provided with the shapefiles? I didn’t know that it was possible to have a shapefile without any kind of spatial reference stored in the metadata. You could try making a location based on the shapefile as a georeferenced file.

Well - as far as I know, the projection info comes in a .prj file (missing) and the .shp file efectively contains the points, dbf the attribute table and the shx the spatial index - no metadata.
All the data I have is the data - no metadata.
Here is the output from ogrinfo:

$ ogrinfo kcla_boundary.shp
INFO: Open of kcla_boundary.shp' using driver ESRI Shapefile’ successful.
1: kcla_boundary (Line String)
rkrug@ecolmod:~/Documents/Projects/HakeaLandscape/trunc/GIS/locations/Keurboom/region$ ogrinfo -al kcla_boundary.shp
INFO: Open of kcla_boundary.shp' using driver ESRI Shapefile’ successful.

Layer name: kcla_boundary
Geometry: Line String
Feature Count: 1
Extent: (17001.174423, -3754438.151804) - (37019.926542, -3743929.774592)
Layer SRS WKT:
(unknown)
ID: Integer (8.0)
OGRFeature(kcla_boundary):0
ID (Integer) = 0
LINESTRING (36961.220524529955583 -3748802.374081357847899,34701.038833641323436 -3749477.493287727236748,30885.147667205979815 -3747804.371776290237904,26218.019240565823566 -3746336.721327661070973,21316.066742145034368 -3743929.774591909721494,19877.769302488635731 -3745749.661148209590465,18821.060979475769273 -3745544.19008540129289,17470.822566737107991 -3746160.603273825719953,17001.174423175834818 -3748362.078946769237518,21169.301697282135137 -3750152.612494096625596,24368.77967529331363 -3750181.965503069106489,26276.725258510985441 -3751855.087014506105334,28360.788895564135601 -3753234.678436217363924,30591.617577480181353 -3754438.151804093271494,32323.44510686238209 -3753674.973570805974305,27715.022698167384078 -3751708.321969643235207,27509.55163535932661 -3750739.672673548106104,30180.675451864066417 -3750035.200458206236362,34025.919627271992795 -3751737.6749786157161,37019.92654247511382 -3748861.080099302809685)

Thanks,

Rainer

Best,
Daniel

–
B.Sc. Daniel Lee
Geschäftsführung für Forschung und Entwicklung
ISIS - International Solar Information Solutions

Deutschhausstr. 10
35037 Marburg
Festnetz: +49 6421 379 6256
Mobil: +49 176 6127 7269
E-Mail: Lee@isi-solutions.org
Web: http://www.isi-solutions.org

Am 05.07.2011 12:59 schrieb “Rainer M Krug” <r.m.krug@gmail.com>:

Hi

I have two shape files of which I do not know the projection (and it seems
that the person I got them from does not know either…). The maps are from
the Keurboom nature reserve area in South Africa (
http://plak.co.za/moreinfo.php?id=347) and the two shp files have the
folowing bounding boxes:

In layer spatial reference system units : xMin,yMin 21340.4,-3755528.75 :
xMax,yMax 34244.9,-3749187.87

In layer spatial reference system units : xMin,yMin 17001.2,-3754438.15 :
xMax,yMax 37019.9,-3743929.77

I know this is a guessing game, but it must be a common projection - the map
datum is very likely (almost certainly) WGS84.

Any suggestions welcome,

Rainer

–
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel : +33 - (0)9 53 10 27 44
Cell: +33 - (0)6 85 62 59 98
Fax (F): +33 - (0)9 58 10 27 44

Fax (D): +49 - (0)3 21 21 25 22 44

email: Rainer@krugs.de

Skype: RMkrug

–
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel : +33 - (0)9 53 10 27 44
Cell: +33 - (0)6 85 62 59 98
Fax (F): +33 - (0)9 58 10 27 44

Fax (D): +49 - (0)3 21 21 25 22 44

email: Rainer@krugs.de

Skype: RMkrug

4

Hi Rainer
I'm not sure where Keurboom nature reserve is, but South Africa uses
transverse Metacor. So it probablity one of the following projections, just
the +lon_0 changes.

+proj=tmerc +lat_0=0 +lon_0=25.00000000000003 +k=1 +x_0=0 +y_0=0 +ellps=WGS84
+towgs84=0,0,0,0,0,0,0 +units=m +datum=WGS84 +no_defs

+proj=tmerc +lat_0=0 +lon_0=27.00000000000003 +k=1 +x_0=0 +y_0=0 +ellps=WGS84
+towgs84=0,0,0,0,0,0,0 +units=m +datum=WGS84 +no_defs

+proj=tmerc +lat_0=0 +lon_0=29.00000000000003 +k=1 +x_0=0 +y_0=0 +ellps=WGS84
+towgs84=0,0,0,0,0,0,0 +units=m +datum=WGS84 +no_defs

+proj=tmerc +lat_0=0 +lon_0=31.00000000000003 +k=1 +x_0=0 +y_0=0 +ellps=WGS84
+towgs84=0,0,0,0,0,0,0 +units=m +datum=WGS84 +no_defs

Lester

On Tuesday 05 July 2011 12:52:01 Rainer M Krug wrote:

Hi

I have two shape files of which I do not know the projection (and it seems
that the person I got them from does not know either...). The maps are from
the Keurboom nature reserve area in South Africa (
http://plak.co.za/moreinfo.php?id=347) and the two shp files have the
folowing bounding boxes:

In layer spatial reference system units : xMin,yMin 21340.4,-3755528.75 :
xMax,yMax 34244.9,-3749187.87

In layer spatial reference system units : xMin,yMin 17001.2,-3754438.15 :
xMax,yMax 37019.9,-3743929.77

I know this is a guessing game, but it must be a common projection - the
map datum is very likely (almost certainly) WGS84.

Any suggestions welcome,

Rainer

5

On Tue, Jul 5, 2011 at 1:17 PM, Rainer M Krug <r.m.krug@gmail.com> wrote:

On Tue, Jul 5, 2011 at 1:05 PM, Daniel Lee <lee@isi-solutions.org> wrote:

That really is a guessing game, because even if someone finds the
coordinates that the map could fit into, it still doesn't mean that they're
correct. Do you have a reason to think that the datum is WGS84? I think
South Africa probably uses a more accurate regional datum for local maps -
that makes a lot more sense unless you're working directly with web mapping
applications or you want to use GPS data directly.

Yes - everybody is using WGS84, because it comes from a GPS - and
reprojection usually is to be avoided because it is difficult to understand
(I am allowed this statement - I have lived in SA and really loved it
there!).

A datum commonly used in South Africa is Hartebeeshoek94, another one
is the Cape Datum coordinate system. Some topographical maps for South
Africa use a CRS with datum Hartebeeshoek94 and come together with
instructions on how to set up your GPS to use this CRS, so you don't
get lost when hiking.

IOW, at least in South Africa datums other than WGS84 are common.

Isn't there any metadata provided with the shapefiles? I didn't know that
it was possible to have a shapefile without any kind of spatial reference
stored in the metadata. You could try making a location based on the
shapefile as a georeferenced file.

Well - as far as I know, the projection info comes in a .prj file (missing)
and the .shp file efectively contains the points, dbf the attribute table
and the shx the spatial index - no metadata.
All the data I have is the data - no metadata.
Here is the output from ogrinfo:
$ ogrinfo kcla_boundary.shp
INFO: Open of `kcla_boundary.shp'
using driver `ESRI Shapefile' successful.
1: kcla_boundary (Line String)
rkrug@ecolmod:~/Documents/Projects/HakeaLandscape/trunc/GIS/locations/Keurboom/region$
ogrinfo -al kcla_boundary.shp
INFO: Open of `kcla_boundary.shp'
using driver `ESRI Shapefile' successful.
Layer name: kcla_boundary
Geometry: Line String
Feature Count: 1
Extent: (17001.174423, -3754438.151804) - (37019.926542, -3743929.774592)
Layer SRS WKT:
(unknown)
ID: Integer (8.0)
OGRFeature(kcla_boundary):0
ID (Integer) = 0
LINESTRING (36961.220524529955583
-3748802.374081357847899,34701.038833641323436
-3749477.493287727236748,30885.147667205979815
-3747804.371776290237904,26218.019240565823566
-3746336.721327661070973,21316.066742145034368
-3743929.774591909721494,19877.769302488635731
-3745749.661148209590465,18821.060979475769273
-3745544.19008540129289,17470.822566737107991
-3746160.603273825719953,17001.174423175834818
-3748362.078946769237518,21169.301697282135137
-3750152.612494096625596,24368.77967529331363
-3750181.965503069106489,26276.725258510985441
-3751855.087014506105334,28360.788895564135601
-3753234.678436217363924,30591.617577480181353
-3754438.151804093271494,32323.44510686238209
-3753674.973570805974305,27715.022698167384078
-3751708.321969643235207,27509.55163535932661
-3750739.672673548106104,30180.675451864066417
-3750035.200458206236362,34025.919627271992795
-3751737.6749786157161,37019.92654247511382 -3748861.080099302809685)
Thanks,
Rainer

Best,
Daniel

--
B.Sc. Daniel Lee
Geschäftsführung für Forschung und Entwicklung
ISIS - International Solar Information Solutions

Deutschhausstr. 10
35037 Marburg
Festnetz: +49 6421 379 6256
Mobil: +49 176 6127 7269
E-Mail: Lee@isi-solutions.org
Web: http://www.isi-solutions.org

Am 05.07.2011 12:59 schrieb "Rainer M Krug" <r.m.krug@gmail.com>:
> Hi
>
> I have two shape files of which I do not know the projection (and it
> seems
> that the person I got them from does not know either...). The maps are
> from
> the Keurboom nature reserve area in South Africa (
> http://plak.co.za/moreinfo.php?id=347) and the two shp files have the
> folowing bounding boxes:
>
>
> In layer spatial reference system units : xMin,yMin 21340.4,-3755528.75
> :
> xMax,yMax 34244.9,-3749187.87
>
> In layer spatial reference system units : xMin,yMin 17001.2,-3754438.15
> :
> xMax,yMax 37019.9,-3743929.77
>
>
> I know this is a guessing game, but it must be a common projection - the
> map
> datum is very likely (almost certainly) WGS84.
>
>
> Any suggestions welcome,
>
>
> Rainer
>
>
> --
> Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
> Biology,
> UCT), Dipl. Phys. (Germany)
>
> Centre of Excellence for Invasion Biology
> Stellenbosch University
> South Africa
>
> Tel : +33 - (0)9 53 10 27 44
> Cell: +33 - (0)6 85 62 59 98
> Fax (F): +33 - (0)9 58 10 27 44
>
> Fax (D): +49 - (0)3 21 21 25 22 44
>
> email: Rainer@krugs.de
>
> Skype: RMkrug

--
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel : +33 - (0)9 53 10 27 44
Cell: +33 - (0)6 85 62 59 98
Fax (F): +33 - (0)9 58 10 27 44

Fax (D): +49 - (0)3 21 21 25 22 44

email: Rainer@krugs.de

Skype: RMkrug

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6

On 05/07/11 12:52, Rainer M Krug wrote:

Hi

I have two shape files of which I do not know the projection (and it
seems that the person I got them from does not know either...). The maps
are from the Keurboom nature reserve area in South Africa
(http://plak.co.za/moreinfo.php?id=347) and the two shp files have the
folowing bounding boxes:

In layer spatial reference system units : xMin,yMin 21340.4,-3755528.75
: xMax,yMax 34244.9,-3749187.87

In layer spatial reference system units : xMin,yMin 17001.2,-3754438.15
: xMax,yMax 37019.9,-3743929.77

I know this is a guessing game, but it must be a common projection - the
map datum is very likely (almost certainly) WGS84.

Any suggestions welcome,

Next to Lester's precise suggestions, this would be my path of choice:

Search for Type='projected CRS' and Area='South Africe' here: http://www.epsg-registry.org/ and then see which of these seem to fit.

Moritz