Re: [gdal-dev] Problems with OGRGeometry Intersects

2012-09-05 Thread Gabriel Fusca 
Hi,

Thanks for the answer.

 OGRPoint querypoint = OGRPoint(Point.x_, Point.y_);
 querypoint.assignSpatialReference(new OGRSpatialReference(SrWkt.c_str()));

It is not necessary to transform the query point because the Point is at
the same spatial reference system.

 pgeometry-Intersects(pquerypoly)

Intersects perform a transformation to verify the intersection of the
geometries? The two geometries (the one that came from the point and the
other that want to intersect) have two different spatial reference systems.

point - EPSG 4326 (GEO)
other geometry - (WGS 84 /  UTM zone 21S) (PROJ)

Thanks,
Regards,


2012/9/4 Even Rouault even.roua...@mines-paris.org

 Le mardi 04 septembre 2012 23:04:16, Gabriel Fusca a écrit :
  Hi,
 
  I'm using Gdal 1.9.
 
  I have a function that has to perform a intersection of a geometry based
 on
  the click that is made on the screen.
 
  The raster file (Geotiff) that has a projected reference system (WGS 84 /
  UTM zone 21S)  and the geometry a georeferenced system (EPSG - 4326
 WGS84).
 
  The click that comes from the screen (spatial reference of the image)
  create a geometry from calling point.Buffer (radius).
 
  When i want to verify that the geometries intersect the intersects method
  from OGRGeometry fails, even if the querypoint is transformed into the
  spatial reference system of the geometry.
 
  Envelopes from the 2 geometries.
  QueryPoint
  env.
  if i generates the querypoint from the spatial reference of the geometry
  that i want to intersect)
  minx -61.66, maxx -53.66;
  miny -41.97, maxy -33.97
  else
  minx 443322.50, maxx 443330.50
  miny 5798153.59, maxy 5798161.59
 
  Geometry env.
  minx -57.79, maxx -57.59;
  miny -38.08, maxy-37.92
 
 
  The code is something like this:
 
  // spatialfilterwindow image subset transformed into
  // the spatial reference of the vector to intersect
  Extent spatialfilter(spatialfilterwindow);
  player-SetSpatialFilterRect(spatialfilter.min_.x_,
  spatialfilter.min_.y_,
  spatialfilter.max_.x_,
  spatialfilter.max_.y_);
  OGRLayer* player = ...;
  OGRFeature *pfeature = player-GetNextFeature();
  OGRPoint querypoint = OGRPoint(Point.x_, Point.y_);
  querypoint.assignSpatialReference(new
 OGRSpatialReference(SrWkt.c_str()));
  OGRGeometry* pquerypoly = querypoint.Buffer(radius);
   *while *(pfeature) {
  OGRGeometry *pgeometry = pfeature-GetGeometryRef();
  *if *((pgeometry  pgeometry-Intersects(pquerypoly) == TRUE)
 
  || (pquerypoly  pquerypoly-Intersects(pgeometry) == TRUE)) {
 
  // do something...
  } *else *{
  // handle the intersection fail
  }
  pfeature = player-GetNextFeature();
  }
 
  Any idea why it fails?

 I suspect that you assumed assignSpatialReference() would do the
 reprojection,
 which isn't the case (it just blindly assigns the specified SRS, but
 doesn't
 alter the geometry coordinates). You must use the TransformTo() method
 instead.

 Incidental comment : you don't need to test ( A-Insersects(B) || B-
 Insersects(A)). Intersects() is a symetrical operation, so just one test
 will
 be enough.

 
  Thanks,
  Regards,




-- 
Gabriel Fusca
SUR Emprendimientos Tecnológicos

Perú 345  Piso 5to Oficina B (C1067AAG)
Ciudad de Buenos Aires, Argentina
Tel. +54 (11) 4342-2976/84
gabrielfu...@suremptec.com.ar
http://www.suremptec.com/
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Re: [gdal-dev] Problems with OGRGeometry Intersects

2012-09-05 Thread Even Rouault 
Selon Gabriel Fusca gabrielfu...@suremptec.com.ar:

 Hi,

 Thanks for the answer.

  OGRPoint querypoint = OGRPoint(Point.x_, Point.y_);
  querypoint.assignSpatialReference(new OGRSpatialReference(SrWkt.c_str()));

 It is not necessary to transform the query point because the Point is at
 the same spatial reference system.

Good.


  pgeometry-Intersects(pquerypoly)

 Intersects perform a transformation to verify the intersection of the
 geometries?

No. The geometries passed to Intersects (and all other methods that take 2
geometries as input) must be in the same SRS. So you have to transform one of
them to the SRS of the other with TransformTo().
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Re: [gdal-dev] Problems with OGRGeometry Intersects

2012-09-05 Thread Gabriel Fusca 
Hi,

Thanks Even! This solves the problem!



2012/9/5 Even Rouault even.roua...@mines-paris.org

 Selon Gabriel Fusca gabrielfu...@suremptec.com.ar:

  Hi,
 
  Thanks for the answer.
 
   OGRPoint querypoint = OGRPoint(Point.x_, Point.y_);
   querypoint.assignSpatialReference(new
 OGRSpatialReference(SrWkt.c_str()));
 
  It is not necessary to transform the query point because the Point is at
  the same spatial reference system.

 Good.

 
   pgeometry-Intersects(pquerypoly)
 
  Intersects perform a transformation to verify the intersection of the
  geometries?

 No. The geometries passed to Intersects (and all other methods that take 2
 geometries as input) must be in the same SRS. So you have to transform one
 of
 them to the SRS of the other with TransformTo().




-- 
Gabriel Fusca
SUR Emprendimientos Tecnológicos

Perú 345  Piso 5to Oficina B (C1067AAG)
Ciudad de Buenos Aires, Argentina
Tel. +54 (11) 4342-2976/84
gabrielfu...@suremptec.com.ar
http://www.suremptec.com/
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[gdal-dev] Problems with OGRGeometry Intersects

2012-09-04 Thread Gabriel Fusca 
Hi,

I'm using Gdal 1.9.

I have a function that has to perform a intersection of a geometry based on
the click that is made on the screen.

The raster file (Geotiff) that has a projected reference system (WGS 84 /
UTM zone 21S)  and the geometry a georeferenced system (EPSG - 4326 WGS84).

The click that comes from the screen (spatial reference of the image)
create a geometry from calling point.Buffer (radius).

When i want to verify that the geometries intersect the intersects method
from OGRGeometry fails, even if the querypoint is transformed into the
spatial reference system of the geometry.

Envelopes from the 2 geometries.
QueryPoint
env.
if i generates the querypoint from the spatial reference of the geometry
that i want to intersect)
minx -61.66, maxx -53.66;
miny -41.97, maxy -33.97
else
minx 443322.50, maxx 443330.50
miny 5798153.59, maxy 5798161.59

Geometry env.
minx -57.79, maxx -57.59;
miny -38.08, maxy-37.92


The code is something like this:

// spatialfilterwindow image subset transformed into
// the spatial reference of the vector to intersect
Extent spatialfilter(spatialfilterwindow);
player-SetSpatialFilterRect(spatialfilter.min_.x_,
spatialfilter.min_.y_,
spatialfilter.max_.x_,
spatialfilter.max_.y_);
OGRLayer* player = ...;
OGRFeature *pfeature = player-GetNextFeature();
OGRPoint querypoint = OGRPoint(Point.x_, Point.y_);
querypoint.assignSpatialReference(new OGRSpatialReference(SrWkt.c_str()));
OGRGeometry* pquerypoly = querypoint.Buffer(radius);
 *while *(pfeature) {
OGRGeometry *pgeometry = pfeature-GetGeometryRef();
*if *((pgeometry  pgeometry-Intersects(pquerypoly) == TRUE)
|| (pquerypoly  pquerypoly-Intersects(pgeometry) == TRUE)) {
// do something...
} *else *{
// handle the intersection fail
}
pfeature = player-GetNextFeature();
}

Any idea why it fails?

Thanks,
Regards,

-- 
Gabriel Fusca
SUR Emprendimientos Tecnológicos

Perú 345  Piso 5to Oficina B (C1067AAG)
Ciudad de Buenos Aires, Argentina
Tel. +54 (11) 4342-2976/84
gabrielfu...@suremptec.com.ar
http://www.suremptec.com/
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Re: [gdal-dev] Problems with OGRGeometry Intersects

2012-09-04 Thread Even Rouault 
Le mardi 04 septembre 2012 23:04:16, Gabriel Fusca a écrit :
 Hi,
 
 I'm using Gdal 1.9.
 
 I have a function that has to perform a intersection of a geometry based on
 the click that is made on the screen.
 
 The raster file (Geotiff) that has a projected reference system (WGS 84 /
 UTM zone 21S)  and the geometry a georeferenced system (EPSG - 4326 WGS84).
 
 The click that comes from the screen (spatial reference of the image)
 create a geometry from calling point.Buffer (radius).
 
 When i want to verify that the geometries intersect the intersects method
 from OGRGeometry fails, even if the querypoint is transformed into the
 spatial reference system of the geometry.
 
 Envelopes from the 2 geometries.
 QueryPoint
 env.
 if i generates the querypoint from the spatial reference of the geometry
 that i want to intersect)
 minx -61.66, maxx -53.66;
 miny -41.97, maxy -33.97
 else
 minx 443322.50, maxx 443330.50
 miny 5798153.59, maxy 5798161.59
 
 Geometry env.
 minx -57.79, maxx -57.59;
 miny -38.08, maxy-37.92
 
 
 The code is something like this:
 
 // spatialfilterwindow image subset transformed into
 // the spatial reference of the vector to intersect
 Extent spatialfilter(spatialfilterwindow);
 player-SetSpatialFilterRect(spatialfilter.min_.x_,
 spatialfilter.min_.y_,
 spatialfilter.max_.x_,
 spatialfilter.max_.y_);
 OGRLayer* player = ...;
 OGRFeature *pfeature = player-GetNextFeature();
 OGRPoint querypoint = OGRPoint(Point.x_, Point.y_);
 querypoint.assignSpatialReference(new OGRSpatialReference(SrWkt.c_str()));
 OGRGeometry* pquerypoly = querypoint.Buffer(radius);
  *while *(pfeature) {
 OGRGeometry *pgeometry = pfeature-GetGeometryRef();
 *if *((pgeometry  pgeometry-Intersects(pquerypoly) == TRUE)
 
 || (pquerypoly  pquerypoly-Intersects(pgeometry) == TRUE)) {
 
 // do something...
 } *else *{
 // handle the intersection fail
 }
 pfeature = player-GetNextFeature();
 }
 
 Any idea why it fails?

I suspect that you assumed assignSpatialReference() would do the reprojection, 
which isn't the case (it just blindly assigns the specified SRS, but doesn't 
alter the geometry coordinates). You must use the TransformTo() method 
instead.

Incidental comment : you don't need to test ( A-Insersects(B) || B-
Insersects(A)). Intersects() is a symetrical operation, so just one test will 
be enough. 

 
 Thanks,
 Regards,
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