Tyler,
Hopefully your expectations aren't too high. Here it is...
Best Regards,
Brent Fraser
On 3/2/2011 11:34 AM, Tyler Mitchell wrote:
Brent, I'm sure a few of us are interested - sounds good! :)
Tyler
On 2011-03-02, at 8:28 AM, Dan Putler wrote:
Hi Brent,
I can compile C++, and I'm interested. Is it possible to access the code?
Dan
On 03/02/2011 07:04 AM, Brent Fraser wrote:
Dan,
I've got some C++ code that uses GDAL (with a GEOS Union call) to
dissolve polygons based on an attribute. If you can compile C++ code on
Linux, you're welcome to it.
Best Regards,
Brent Fraser
On 3/2/2011 12:31 AM, Dan Putler wrote:
Hi Paolo,
Your point is well taken. What seem to be the best solutions involve
reading in a shapefile and then writing out a new one. I was starting
to lean toward either PostGIS or Spatialite by using a SQL script
sourced within the relevant cli shell since my guess was that they
would scale much better than any Python code I was likely to write. I
think I could automate things more with GRASS shell scripts than with
SQL scripts (there are over 3000 counties in the US). The geometry
cleaning GRASS does is a two edged sword, having all the benefits you
indicate, but at the cost of increased processing time. However, my
guess is that the benefits of the cleaning are worth the cost.
Thanks for your advise.
Dan
On 03/01/2011 10:57 PM, Paolo Cavallini wrote:
Il giorno mar, 01/03/2011 alle 23.25 +0100, Paolo Corti ha scritto:
Your only option here could be to use GRASS, but as far as I know you
need to import your shapefile to the GRASS database, use a GRASS
command (v.reclass [0]) and export back to shapefile the result, so it
is not very direct.
Not very direct, but it's only one more command (v.in.ogr), with the
additional bonus that importing into GRASS you can clean up invalid
topologies, close empty gaps, remove unwanted overlaps, etc.
All the best.
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/* ***************** SOURCE HEADER: **********************
Copyright (c) 2008 GeoAnalytic Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
Name:
Purpose:
Invocation:
Arguments:
Data Files Accessed:
Program History:
v1.0 19 Aug 2007 BF initial coding
Note:
Algorithm Description:
Future Enhancements:
*************** End of SOURCE HEADER ************** */
#include <assert.h>
#include "GDAL.h"
#include "cpl_string.h"
#include "ogrsf_frmts.h"
/************************************************************************/
typedef struct s_attribute
{
const char *value;
struct s_attribute *next; // list link
} t_attribute;
t_attribute *attributeNew()
{
t_attribute *attribute;
attribute = (t_attribute *) malloc(sizeof(t_attribute));
attribute->value = NULL;
attribute->next = NULL;
return(attribute);
}
void attributeInsert(t_attribute **head, const char* newValue )
{
t_attribute *curr;
t_attribute *prev=NULL;
t_attribute *item=NULL;
curr = *head;
while(curr != NULL)
{
if( strcmp( curr->value , newValue) >= 0 )
break;
prev = curr;
curr = curr->next;
}
if ( !curr || strcmp(curr->value, newValue) != 0 ) //insert a new
node in the list
{
item = attributeNew();
item->value = newValue;
if(prev == NULL)
{
item->next = *head; // new top
*head = item; // link to old top
}else
{
prev->next = item;
item->next = curr;
}
}
return;
}
void attributePrint( t_attribute *head)
{
t_attribute *curr;
curr =head;
while(curr != NULL)
{
printf("%s\n",curr->value );
curr = curr->next;
}
return;
}
int attributeCount( t_attribute *head)
{
int i=0;
t_attribute *curr;
curr =head;
while(curr != NULL)
{
i++;
curr = curr->next;
}
return(i);
}
/************************************************************************/
/************************************************************************/
static void Usage()
{
printf(
"ogrDissolve v1.0\n"
"Dissolves common boundaries between polygons with the same
attribute value.\n"
"Usage: ogrDissolve [-a <attr name>] [-u] <input DS> <output DS>\n" );
exit( 1 );
}
/************************************************************************/
/************************************************************************/
void notice(const char *fmt, ...)
{
va_list ap;
fprintf( stdout, "NOTICE: ");
va_start (ap, fmt);
vfprintf( stdout, fmt, ap);
va_end(ap);
fprintf( stdout, "\n" );
}
void log_and_exit(const char *fmt, ...)
{
va_list ap;
fprintf( stdout, "ERROR: ");
va_start (ap, fmt);
vfprintf( stdout, fmt, ap);
va_end(ap);
fprintf( stdout, "\n" );
exit(1);
}
/************************************************************************/
/* Main() */
/************************************************************************/
int main( int argc, char *argv[] )
{
const char *pszUnionAttrib = NULL;
const char *pszSrcFilename = NULL;
const char *pszDstFilename = NULL;
char *pzsDstFormat = NULL;
char *pzsDstFormatDefault = "ESRI Shapefile";
int i;
bool bUnpackMultiPolys = false;
bool bVerbose = false;
char pszQuery[250];
/* -------------------------------------------------------------------- */
/* Parse arguments. */
/* -------------------------------------------------------------------- */
argc = GDALGeneralCmdLineProcessor( argc, &argv, 0 );
if( argc < 1 )
return( -argc );
if( argc == 1 )
Usage();
for( i = 1; i < argc; i++ )
{
if( EQUAL(argv[i],"-a") && i < argc-1 )
pszUnionAttrib = argv[++i]; // location (path) attribute
name
else if( EQUAL(argv[i],"-u") )
bUnpackMultiPolys = true;
else if( EQUAL(argv[i],"-v") )
bVerbose = true;
else if( EQUAL(argv[i],"-of") && i < argc-1 )
pzsDstFormat = argv[++i];
else if( pszSrcFilename == NULL )
{
pszSrcFilename = argv[i];
}
else if( pszDstFilename == NULL )
{
pszDstFilename = argv[i];
}
else
Usage();
}
if( pszSrcFilename == NULL )
{
CPLError( CE_Failure, CPLE_AppDefined, "An input DataSet is required."
);
return(1);
}
if( pszDstFilename == NULL )
{
CPLError( CE_Failure, CPLE_AppDefined, "An output DataSet is required."
);
return(2);
}
if ( pzsDstFormat == NULL )
{
pzsDstFormat = pzsDstFormatDefault;
}
/* -------------------------------------------------------------------- */
/* Do requested Operations: */
/* -------------------------------------------------------------------- */
OGRDataSource *poDS;
OGRLayer *poLayer;
OGRFeature *poFeature;
OGRFeatureDefn *poFDefn;
OGRGeometry *poGeometry;
OGRwkbGeometryType poGeomType;
// OGRDataSource *poUnionDS;
// OGRLayer *poUnionLayer;
// OGRFeature *poUnionFeature;
OGRDataSource *poDSout;
OGRLayer *poLayerOut;
char *pszGeom=NULL;
long nLayers = 0;
long nFeatures = 0;
long iField = 0;
const char *pzOverlapLocation=NULL;
const char *pzSidLocation=NULL;
bool bFoundAttrib = FALSE;
/*-----------------------------------------------------------------------*/
/* Open input, check for requirements:
*/
/*-----------------------------------------------------------------------*/
OGRRegisterAll();
poDS = OGRSFDriverRegistrar::Open( pszSrcFilename, FALSE ); // we will be
updating the dataset
if( poDS == NULL )
{
return(101); //can't open dataset
}
nLayers = poDS->GetLayerCount();
if (nLayers == 0)
{
return(102); //no layers in dataset
}
// TBD: allow mult layers:
poLayer = poDS->GetLayer( 0 );
poLayer->ResetReading();
nFeatures = poLayer->GetFeatureCount();
if ( (poFeature = poLayer->GetNextFeature()) != NULL )
{
//--- Check Geometry type: ---//
poGeometry = poFeature->GetGeometryRef();
if( poGeometry != NULL )
{
poGeomType = poGeometry->getGeometryType(); // TBD:
check if polgon
if ( poGeomType != wkbMultiPolygon && poGeomType !=
wkbPolygon )
{
printf("Data must be polygons.\n");
}
}else
{
return(104); //no geometry in feature
}
//--- Get Field of Union Attribute: ---//
OGRFeatureDefn *poFDefn = poLayer->GetLayerDefn();
for( iField = 0; iField < poFDefn->GetFieldCount(); iField++ )
{
OGRFieldDefn *poFieldDefn = poFDefn->GetFieldDefn( iField );
if ( EQUAL(poFieldDefn->GetNameRef(),pszUnionAttrib) )
{
bFoundAttrib = true;
break;
}
}
if (!bFoundAttrib)
{
printf("Data must have a disolve field.\n");
return(105);
}
}else
{
printf("No features in dataset.\n");
return(103); //no features in dataset
}
/*-----------------------------------------------------------------------*/
/* Create Attribute List:
*/
/*-----------------------------------------------------------------------*/
poLayer->ResetReading();
i = 0;
const char *pszAttrValue;
t_attribute *attrList=NULL;
while( (poFeature = poLayer->GetNextFeature()) != NULL )
{
// i++;
// GDALTermProgress( ((double)i)/nFeatures, "", NULL);
pszAttrValue = poFeature->GetFieldAsString(iField);
attributeInsert( &attrList, pszAttrValue );
}
// attributePrint(attrList);
/*-----------------------------------------------------------------------*/
/* Create output:
*/
/*-----------------------------------------------------------------------*/
OGRSFDriver *poDriver;
poDriver = OGRSFDriverRegistrar::GetRegistrar()->GetDriverByName(
pzsDstFormat );
if( poDriver == NULL )
{
// printf( "%s driver not available.\n", pszDriverName );
return(101);
}
poDSout = poDriver->CreateDataSource( pszDstFilename, NULL );
if( poDSout == NULL )
{
// printf( "Creation of output file failed.\n" );
return(102);
}
poLayerOut = poDSout->CreateLayer( "new_layer", NULL, poGeomType, NULL
);
if( poLayerOut == NULL )
{
// printf( "Layer creation failed.\n" );
return(103);
}
poFDefn = poLayer->GetLayerDefn();
for(int iField2 = 0; iField2 < poFDefn->GetFieldCount(); iField2++ )
{
OGRFieldDefn *poFieldDefn = poFDefn->GetFieldDefn( iField2 );
if( poLayerOut->CreateField( poFieldDefn ) != OGRERR_NONE )
{
// printf( "Creation of field failed.\n" );
return(104);
}
}
/*-----------------------------------------------------------------------*/
/* Process Features:
*/
/*-----------------------------------------------------------------------*/
poLayer->ResetReading();
i = 0;
t_attribute *curr = attrList;
int nAttrs = attributeCount(attrList);
OGRGeometryCollection *poCollection = new OGRGeometryCollection();
while ( curr )
{
i++;
if (!bVerbose )
GDALTermProgress( ((double)i)/nAttrs, "", NULL);
else
printf("%d/%d. '%s'\n",i,nAttrs,curr->value);
// poLayer->ResetReading();
sprintf( pszQuery, "%s='%s'",pszUnionAttrib, curr->value );
poLayer->SetAttributeFilter( pszQuery );
poLayer->ResetReading();
int nFeatures = poLayer->GetFeatureCount();
OGRGeometry *poGeometryOut=NULL;
// poCollection->empty();
int k=0;
while ( (poFeature = poLayer->GetNextFeature()) )
{
k++;
if (bVerbose )
GDALTermProgress( ((double)k)/nFeatures, "",
NULL);
OGRGeometry *poGeometryTemp=NULL;
poGeometryTemp = poFeature->GetGeometryRef();
if (poGeometryTemp)
{
// if ( poGeometryTemp->IsValid() )
// {
//
poCollection->addGeometry(poGeometryTemp);
// }else
// {
//
poCollection->addGeometry(poGeometryTemp->Buffer(0));
// }
if (poGeometryOut)
{
poGeometryOut = poGeometryOut->Union(
poGeometryTemp);
}else
{
poGeometryOut = poGeometryTemp->clone();
}
}
}
// poGeometryOut = poCollection->Buffer(0);
// force to a collection of polygons
//poCollection->addGeometry( poGeometryOut );
if (bVerbose )
GDALTermProgress( ((double)nFeatures)/nFeatures, "",
NULL);
if (poGeometryOut)
{
char * pszTemp=NULL;
// poGeometryOut->exportToWkt(&pszTemp);
if ( poGeometryOut->getGeometryType() ==
wkbMultiPolygon ) //it's a collection
{
int nPolys = ((OGRGeometryCollection
*)poGeometryOut)->getNumGeometries();
OGRGeometry *poGeometryTemp=NULL;
for (int j=0;j<nPolys;j++ )
{
poGeometryTemp =
((OGRGeometryCollection *)poGeometryOut)->getGeometryRef(j);
OGRFeature *poFeatureOut = new
OGRFeature( poLayer->GetLayerDefn() );
poFeatureOut->SetField( iField,
curr->value );
poFeatureOut->SetGeometryDirectly(poGeometryTemp);
poLayerOut->CreateFeature(poFeatureOut);
}
}else
{
OGRFeature *poFeatureOut = new OGRFeature(
poLayer->GetLayerDefn() );
poFeatureOut->SetField( iField, curr->value );
poFeatureOut->SetGeometryDirectly(poGeometryOut);
poLayerOut->CreateFeature(poFeatureOut);
}
}
curr = curr->next;
}
GDALTermProgress( ((double)nAttrs)/nAttrs, "", NULL);
// printf("\n-- Info: .\n" );
OGRDataSource::DestroyDataSource( poDS );
OGRDataSource::DestroyDataSource( poDSout );
/* -------------------------------------------------------------------- */
/* Exit: */
/* -------------------------------------------------------------------- */
return(0);
}_______________________________________________
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