[geometry] Buffer (with strategy) to offset polygons

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Olivier Tournaire

11 Aug 2014 11 Aug '14

9:41 p.m.

Dear all, I have used successfully the buffering algorithm to offset a shapefile of 2D polygons. However, there are 4 polygons (amongst nearly 4000) in my SHP does are not successfully processed. They do not have topology or orientation errors. I use GDAL 1.9 to read the SHP, boost 1.56 precompiled binaries from sourceforge on a 64bit windows 7. If someone is willing to have a look at the problem, I can share the files and the code I use. Here is a quick overview: typedef double coordinate_type; typedef boost::geometry::model::d2::point_xy point_xy_type; typedef boost::geometry::model::polygon polygon_type; boost::geometry::strategy::buffer::end_flat end_strategy; boost::geometry::strategy::buffer::point_square point_strategy; boost::geometry::strategy::buffer::side_straight side_strategy; boost::geometry::strategy::buffer::distance_symmetric distance_strategy(buffer_distance); boost::geometry::strategy::buffer::join_miter join_strategy(buffer_distance); polygon_type p; boost::geometry::model::multi_polygon result; // Build a polygon_type from OGRPolygon OGRLinearRing* exteriorRing = polygon->getExteriorRing(); for(int i=0;i<exteriorRing->getNumPoints();++i) { OGRPoint pt; exteriorRing->getPoint(i,&pt); p.outer().push_back( point_xy_type(pt.getX(), pt.getY()) ); } for(int i=0;i<polygon->getNumInteriorRings();++i) { OGRLinearRing* interiorRing = polygon->getInteriorRing(i); polygon_type::ring_type ring; for(int j=0;j<interiorRing->getNumPoints();++j) { OGRPoint pt; interiorRing->getPoint(j,&pt); ring.push_back( point_xy_type(pt.getX(), pt.getY()) ); } p.inners().push_back(ring); } boost::geometry::buffer(p, result, distance_strategy, side_strategy, join_strategy, end_strategy, point_strategy); if(result.size() == 0) { int indexID = feature->GetFieldIndex("ID"); cout << "No result build for polygon with ID " << feature->GetFieldAsString(indexID) << endl; } else { typedef boost::geometry::strategy::distance::pythagoras pythagoras_distance_strategy; typedef boost::geometry::strategy::distance::projected_point projected_point_strategy; boost::geometry::strategy::simplify::douglas_peucker dp; OGRPolygon poly; for(size_t i=0;i

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Barend Gehrels

12 Aug 12 Aug

4:14 a.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Hi Olivier, Olivier Tournaire wrote On 11-8-2014 23:41:

...

Dear all,

I have used successfully the buffering algorithm to offset a shapefile of 2D polygons. However, there are 4 polygons (amongst nearly 4000) in my SHP does are not successfully processed. They do not have topology or orientation errors.

I use GDAL 1.9 to read the SHP, boost 1.56 precompiled binaries from sourceforge on a 64bit windows 7. If someone is willing to have a look at the problem, I can share the files and the code I use. Here is a quick overview:

typedef double coordinate_type; typedef boost::geometry::model::d2::point_xy point_xy_type; typedef boost::geometry::model::polygon polygon_type; boost::geometry::strategy::buffer::end_flat end_strategy; boost::geometry::strategy::buffer::point_square point_strategy; boost::geometry::strategy::buffer::side_straight side_strategy;

boost::geometry::strategy::buffer::distance_symmetric distance_strategy(buffer_distance); boost::geometry::strategy::buffer::join_miter join_strategy(buffer_distance);

polygon_type p; boost::geometry::model::multi_polygon result;

// Build a polygon_type from OGRPolygon OGRLinearRing* exteriorRing = polygon->getExteriorRing(); for(int i=0;i<exteriorRing->getNumPoints();++i) { OGRPoint pt; exteriorRing->getPoint(i,&pt);

p.outer().push_back( point_xy_type(pt.getX(), pt.getY()) ); } for(int i=0;i<polygon->getNumInteriorRings();++i) { OGRLinearRing* interiorRing = polygon->getInteriorRing(i); polygon_type::ring_type ring;

for(int j=0;j<interiorRing->getNumPoints();++j) { OGRPoint pt; interiorRing->getPoint(j,&pt);

ring.push_back( point_xy_type(pt.getX(), pt.getY()) ); } p.inners().push_back(ring); }

boost::geometry::buffer(p, result, distance_strategy, side_strategy, join_strategy, end_strategy, point_strategy);

if(result.size() == 0) { int indexID = feature->GetFieldIndex("ID"); cout << "No result build for polygon with ID " << feature->GetFieldAsString(indexID) << endl; } else { typedef boost::geometry::strategy::distance::pythagoras pythagoras_distance_strategy; typedef boost::geometry::strategy::distance::projected_point projected_point_strategy; boost::geometry::strategy::simplify::douglas_peucker dp;

OGRPolygon poly;

for(size_t i=0;i
boost::geometry::simplify(result_i, result_i_simplified, 0.1, dp);

{ OGRLinearRing ring; for(size_t j=0;j
{ OGRLinearRing ring; for(size_t j=0;j
Note that I use a simplification algorithm after buffering to remove colinear points.

Hope you could help.

Thanks for the report. If you can, can you please make WKT's of the 4 failing input (with enough precision)? And send them to me or create a ticket for them? Will look then (might take a while). Regards, Barend

Olivier Tournaire

7:50 p.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Thanks Barend, Do not know where to open a ticket ... Did not find the usual "issues" link on github boost geometry repository. Please let me know where the bug tracker is located. In the meantime, here are the WKT's of the failing input: POLYGON((897866.5 6272518.7,897882.5 6272519.2,897882.6 6272519,897883.3 6272508.7,897883.5 6272505.5,897855 6272503.5,897852.4 6272505.6,897850.1 6272517.6,897860.8 6272518.5,897866.5 6272518.7)) POLYGON((898882.3 6271337.3,898895.7 6271339.9,898898 6271328.3,898881.6 6271325.1,898879.3 6271336.7,898882.3 6271337.3)) POLYGON((897558.7 6272055,897552.5 6272054.2,897552.5 6272053.7,897546.1 6272052.7,897545.6 6272057.7,897560.7 6272059.6,897560.9 6272055.3,897558.7 6272055)) POLYGON((898563.3 6272366.9,898554.7 6272379.2,898559.7 6272382.3,898561.6 6272379.4,898568.7 6272369.1,898563.8 6272366.2,898563.3 6272366.9)) Best regards, Olivier 2014-08-12 6:14 GMT+02:00 Barend Gehrels :

...

Hi Olivier,

Olivier Tournaire wrote On 11-8-2014 23:41:

Dear all,

...
I have used successfully the buffering algorithm to offset a shapefile of 2D polygons. However, there are 4 polygons (amongst nearly 4000) in my SHP does are not successfully processed. They do not have topology or orientation errors.

I use GDAL 1.9 to read the SHP, boost 1.56 precompiled binaries from sourceforge on a 64bit windows 7. If someone is willing to have a look at the problem, I can share the files and the code I use. Here is a quick overview:

typedef double coordinate_type; typedef boost::geometry::model::d2::point_xy point_xy_type; typedef boost::geometry::model::polygon polygon_type; boost::geometry::strategy::buffer::end_flat end_strategy; boost::geometry::strategy::buffer::point_square point_strategy; boost::geometry::strategy::buffer::side_straight side_strategy;

boost::geometry::strategy::buffer::distance_symmetric distance_strategy(buffer_distance); boost::geometry::strategy::buffer::join_miter join_strategy(buffer_distance);

polygon_type p; boost::geometry::model::multi_polygon result;

// Build a polygon_type from OGRPolygon OGRLinearRing* exteriorRing = polygon->getExteriorRing(); for(int i=0;i<exteriorRing->getNumPoints();++i) { OGRPoint pt; exteriorRing->getPoint(i,&pt);

p.outer().push_back( point_xy_type(pt.getX(), pt.getY()) ); } for(int i=0;i<polygon->getNumInteriorRings();++i) { OGRLinearRing* interiorRing = polygon->getInteriorRing(i); polygon_type::ring_type ring;

for(int j=0;j<interiorRing->getNumPoints();++j) { OGRPoint pt; interiorRing->getPoint(j,&pt);

ring.push_back( point_xy_type(pt.getX(), pt.getY()) ); } p.inners().push_back(ring); }

boost::geometry::buffer(p, result, distance_strategy, side_strategy, join_strategy, end_strategy, point_strategy);

if(result.size() == 0) { int indexID = feature->GetFieldIndex("ID"); cout << "No result build for polygon with ID " << feature->GetFieldAsString(indexID) << endl; } else { typedef boost::geometry::strategy:: distance::pythagoras pythagoras_distance_strategy; typedef boost::geometry::strategy:: distance::projected_point projected_point_strategy; boost::geometry::strategy::simplify::douglas_peucker dp;

OGRPolygon poly;

for(size_t i=0;i
boost::geometry::simplify(result_i, result_i_simplified, 0.1, dp);

{ OGRLinearRing ring; for(size_t j=0;j
{ OGRLinearRing ring; for(size_t j=0;j
Note that I use a simplification algorithm after buffering to remove colinear points.

Hope you could help.

Thanks for the report. If you can, can you please make WKT's of the 4 failing input (with enough precision)? And send them to me or create a ticket for them? Will look then (might take a while).

Regards, Barend

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Adam Wulkiewicz

13 Aug 13 Aug

2:03 p.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Hi, Olivier Tournaire wrote:

...

Thanks Barend,

Do not know where to open a ticket ... Did not find the usual "issues" link on github boost geometry repository. Please let me know where the bug tracker is located.

http://www.boost.org/development/bugs.html https://svn.boost.org/trac/boost/newticket Regards, Adam

Olivier Tournaire

25 Aug 25 Aug

9:13 a.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Barend, Adam, Ticket created: https://svn.boost.org/trac/boost/ticket/10398. I attached a sample code to reproduce the problem. Let me know if you need more inputs. Best regards, Olivier 2014-08-13 16:03 GMT+02:00 Adam Wulkiewicz :

...

Hi,

Olivier Tournaire wrote:

...
Thanks Barend,

Do not know where to open a ticket ... Did not find the usual "issues" link on github boost geometry repository. Please let me know where the bug tracker is located.

http://www.boost.org/development/bugs.html https://svn.boost.org/trac/boost/newticket

Regards, Adam

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Barend Gehrels

27 Aug 27 Aug

10:45 a.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Hi Olivier, Olivier Tournaire wrote On 25-8-2014 11:13:

...

Ticket created: https://svn.boost.org/trac/boost/ticket/10398. I attached a sample code to reproduce the problem.

Let me know if you need more inputs.

It is fixed in branch feature/buffer, see ticket Will be released in 1.57 Thanks for the ticket/report Regards, Barend

Olivier Tournaire

11:36 a.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Hi Barend, Thank you so much for your quick fix! I can confirm the problem is solved. I however may have found another bug (just for a single polygon this time, over the same 4000 polygons). The bug was already here before your previous fix. On the attached images, you can see the result of offsetting the input polygon with a 2.5m distance and the same strategies as above. The output is a multipolygon and it seems to be self intersecting. Is it a bug or is it the expected result? In the first case, I can quickly open a ticket with a sample to reproduce the problem. Best regards, Olivier 2014-08-27 12:45 GMT+02:00 Barend Gehrels :

...

Hi Olivier,

Olivier Tournaire wrote On 25-8-2014 11:13:

...
Ticket created: https://svn.boost.org/trac/boost/ticket/10398. I attached a sample code to reproduce the problem.

Let me know if you need more inputs.

It is fixed in branch feature/buffer, see ticket Will be released in 1.57

Thanks for the ticket/report

Regards, Barend

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Olivier Tournaire

11:41 a.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Made a mistake: distance is 1.5m, not 2.5m 2014-08-27 13:36 GMT+02:00 Olivier Tournaire :

...

Hi Barend,

Thank you so much for your quick fix! I can confirm the problem is solved.

I however may have found another bug (just for a single polygon this time, over the same 4000 polygons). The bug was already here before your previous fix.

On the attached images, you can see the result of offsetting the input polygon with a 2.5m distance and the same strategies as above. The output is a multipolygon and it seems to be self intersecting. Is it a bug or is it the expected result? In the first case, I can quickly open a ticket with a sample to reproduce the problem.

Best regards,

Olivier

2014-08-27 12:45 GMT+02:00 Barend Gehrels :

Hi Olivier,

...
Olivier Tournaire wrote On 25-8-2014 11:13:

...
Ticket created: https://svn.boost.org/trac/boost/ticket/10398. I attached a sample code to reproduce the problem.

Let me know if you need more inputs.

It is fixed in branch feature/buffer, see ticket Will be released in 1.57

Thanks for the ticket/report

Regards, Barend

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Barend Gehrels

1:37 p.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Hi Olivier, Olivier Tournaire wrote On 27-8-2014 13:41:

...

Made a mistake: distance is 1.5m, not 2.5m

2014-08-27 13:36 GMT+02:00 Olivier Tournaire mailto:olitour@gmail.com>:

Hi Barend,

Thank you so much for your quick fix! I can confirm the problem is solved.

I however may have found another bug (just for a single polygon this time, over the same 4000 polygons). The bug was already here before your previous fix.

On the attached images, you can see the result of offsetting the input polygon with a 2.5m distance and the same strategies as above. The output is a multipolygon and it seems to be self intersecting. Is it a bug or is it the expected result? In the first case, I can quickly open a ticket with a sample to reproduce the problem.

I somehow missed the first message with attachments. Can you open a new ticket and attach it there? Regards, Barend p.s. this list discourages top postings.

Olivier Tournaire

4:09 p.m.

New subject: [geometry] Buffer (with strategy) to offset polygons

Barend 2014-08-27 15:37 GMT+02:00 Barend Gehrels :

...

Hi Olivier,

Olivier Tournaire wrote On 27-8-2014 13:41:

Made a mistake: distance is 1.5m, not 2.5m

2014-08-27 13:36 GMT+02:00 Olivier Tournaire :

...
Hi Barend,

Thank you so much for your quick fix! I can confirm the problem is solved.

I however may have found another bug (just for a single polygon this time, over the same 4000 polygons). The bug was already here before your previous fix.

On the attached images, you can see the result of offsetting the input polygon with a 2.5m distance and the same strategies as above. The output is a multipolygon and it seems to be self intersecting. Is it a bug or is it the expected result? In the first case, I can quickly open a ticket with a sample to reproduce the problem.

I somehow missed the first message with attachments. Can you open a new ticket and attach it there?

Ticket created: https://svn.boost.org/trac/boost/ticket/10412

...

Regards, Barend

p.s. this list discourages top postings.

oups, sorry. Regards, Olivier

...

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Adam Wulkiewicz
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Olivier Tournaire