Add geometry polyhedral surface #1402

vissarion · 2025-04-30T10:39:22Z

This PR is based on #789 and adds a 3D geometry type for polyhedral surfaces according to OGC standard.

The main class, concepts, i/o and basic traits are added.

Comparing to #789 it refines the code (since that was an old PR and the library evolved since then) and also defines the polyhedral surface as a set of polygons (instead of rings) as described in the standard.

Finally, there are docs and unit tests.

Co-authored-by: Siddharth kumar <[email protected]>

example/08_polyhedralsurface_example.cpp

barendgehrels · 2025-05-02T05:54:29Z

example/08_polyhedralsurface_example.cpp

+    // Write polyhedral surface wkt
+    std::cout << bg::wkt(polyhedral0) << std::endl;
+    std::cout << bg::wkt(polyhedral1) << std::endl;
+    std::cout << bg::wkt(polyhedral2) << std::endl;


Great you picked it up again!

there should be credit to Sidharta in the copyright section

how sure are we that this all works and is according to the standards? Are there rules for ordering faces?

should we check at least one property (for example area or volume) and compare it with another library

or are there ways (other OS tools or so) to visualize it to see we didn't miss anything?

Great you picked it up again!

* there should be credit to Sidharta in the copyright section

I have already added as a commit coauthor, he hasn't added copyright notes in his original PR, but I agree that should be mentioned in copyrights too, so I added. @Siddharth-coder13 please let me know if you agree with those additions.

* how sure are we that this all works and is according to the standards? Are there rules for ordering faces?

We are not sure at this point, that check (consistent orientation of faces) could be part of validity checks. Another check should be related to dimension (assert that is 3). Does it make sense to add this in is_valid too? AFAIU this is similar to the overlapping polygon check for multi_polyogons (that check also applies for polyhedral surfaces).

The standard also defines the following methods (that will be implemented in a subsequent PR):
--- NumPatches () : Integer ⎯ Returns the number of including polygons
--- PatchN (N: Integer): Polygon ⎯ Returns a polygon in this surface, the order is arbitrary.
--- BoundingPolygons (p: Polygon): MultiPolygon ⎯ Returns the collection of polygons in this surface that
bounds the given polygon “p” for any polygon “p” in the surface.
--- IsClosed (): Integer - Returns 1 (True) if the polygon closes on itself, and thus has no boundary and
encloses a solid

* should we check at least one property (for example area or volume) and compare it with another library

Sure, but I think that should be after implementing is_valid and the basic methods above.

* or are there ways (other OS tools or so) to visualize it to see we didn't miss anything?

there are a few visualization software (e.g. geomview) but I do not know of any that supports WKT for polyhedral surfaces.

EDIT: NumPatches () and PatchN (N: Integer) are already implemented by calling size() and [].

include/boost/geometry/geometries/concepts/polyhedral_surface_concept.hpp

include/boost/geometry/geometries/polyhedral_surface.hpp

barendgehrels · 2025-05-02T05:57:32Z

include/boost/geometry/geometries/polyhedral_surface.hpp

+
+/*!
+\brief A Polyhedral Surface is a contiguous collection of polygons,
+    which share common boundary segments.


we don't check it. Suggestion:
"The concepts and algorithms don't check if the boundary segments are common"

I also added that common boundary segments should be checked by is_valid()

include/boost/geometry/io/wkt/read.hpp

include/boost/geometry/io/wkt/write.hpp

test/geometries/polyhedral_surface.cpp

…me structs and templates

vissarion · 2025-05-02T09:59:03Z

Thanks @barendgehrels for the quick review! I've addressed all your comments and replied to questions.

tinko92 · 2025-05-02T14:45:22Z

doc/concept/polyhedral_surface.qbk

+The PolyhedralSurface Concept is defined as following:
+
+* There must be a specialization of the metafunction `traits::tag`, defining `polyhedral_surface_tag` as type
+* It must behave like a Boost.Range Random Access Range


Both ranges and concepts have been standardized in C++20, which BG does not yet depend on, after the definition of the original BG concepts which have existing users. For new BG concepts like this one, which do not have legacy usage that they need to be compatible to, should we consider documenting the requirement as behaving like C++ standard ranges instead?

I'm not sure... we cannot yet make it dependent on C++20 yet...
Also it would be weird to let some concepts depend on the std-ranges/concepts, and others not...

we cannot yet make it dependent on C++20 yet...

Yes. To be clear, my thought was to document it based on the STL concept, not actually bumping the version requirement of the library. The behaviour could be used without depending on the actual C++ version in which it became part of the STL. The rationale is avoiding a future breaking change in this BG concept, if BG moves to a newer standard eventually.

But I understand the point about consistency with existing BG concepts.

tinko92 · 2025-05-02T14:50:16Z

doc/concept/polyhedral_surface.qbk

+
+[heading Description]
+[concept PolyhedralSurface..polyhedral surface]
+


There seems to be text and a reference to the corresponding OGC simple feature missing here.

tinko92 · 2025-05-02T14:57:35Z

include/boost/geometry/algorithms/clear.hpp

@@ -72,6 +72,18 @@ struct polygon_clear
    }
 };

+template <typename Polyhedral_surface>


Shoulds this be PolyhedralSurface (like MultiPoint)?

tinko92 · 2025-05-02T15:00:00Z

include/boost/geometry/io/wkt/write.hpp

@@ -396,6 +420,15 @@ struct wkt<Polygon, polygon_tag>
        >
 {};

+template <typename Polyhedral_surface>


Like previous comment, should this be PolyhedralSurface?

barendgehrels · 2025-05-02T18:31:51Z

doc/src/examples/geometries/polyhedral_surface.cpp

+// Boost.Geometry
+// QuickBook Example
+
+// Copyright (c) 2025 Siddharth Kumar, Roorkee, India.


👍 thanks - and cool that you co-authored, hadn't spotted that indeed.

Thanks @vissarion for mentioning me in the copyrights.

barendgehrels · 2025-05-02T18:48:49Z

doc/src/examples/geometries/polyhedral_surface.cpp

+                                {{{0, 0, 0}, {1, 0, 0}, {1, 0, 1}, {0, 0, 1}, {0, 0, 0}}},
+                                {{{1, 1, 1}, {1, 0, 1}, {0, 0, 1}, {0, 1, 1}, {1, 1, 1}}},
+                                {{{1, 1, 1}, {1, 0, 1}, {1, 0, 0}, {1, 1, 0}, {1, 1, 1}}},
+                                {{{1, 1, 1}, {1, 1, 0}, {0, 1, 0}, {0, 1, 1}, {1, 1, 1}}}}; /*< Creating a polyhedral surface (cube) using standard initialized list >*/


I'm not experienced in this subject. I had to parse it mentally and it is a cube. Then I noticed it is written there - can that comment go first?

Same below - it's nice to have a pyramid, which is kind of realistic. But I think the example is not correct. I would expect at least a point in the center (2.5, 2.5) which is not there. Or it is not a pyramid. Didn't parse the rest...

Maybe a (squarish) pyramid would be a more realistic example. It should have 5 faces, the floor face having 4 points, the other faces having 3 points, if I'm correct. Or the closure points should be added in all faces. The 4 other faces should have one common point in the center.

And then there should a picture of it (somehow, for example in geomview, constructed in another way then).

Writing this gives me also the questions:

should the surfaces be closed? Will it follow the polygon rules?

should they be clockwise? Will it follow the polygon rules?

vissarion and others added 5 commits April 30, 2025 12:51

feat: Create polyhedral surface class

445aaf6

Co-authored-by: Siddharth kumar <[email protected]>

doc: Polyhedral surface

d48155b

chore: Add polyhedral surface example

29bae4f

test: Polyhedral surface

38ac122

chore: Remove unused header

72c43ae

vissarion requested review from barendgehrels, awulkiew and tinko92 April 30, 2025 10:39

vissarion added the enhancement label Apr 30, 2025

barendgehrels reviewed May 2, 2025

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vissarion added 3 commits May 2, 2025 12:08

chore: Fix typos, remove tabs, backslashes from initializations, rena…

5652cbd

…me structs and templates

chore: Remove repeated polyhedral surface example

8c5cfd8

chore: Update copyright notes

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chore: Update examples Jamfile

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Add geometry polyhedral surface #1402

Add geometry polyhedral surface #1402

vissarion commented Apr 30, 2025

barendgehrels May 2, 2025

vissarion May 2, 2025

vissarion May 2, 2025

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vissarion commented May 2, 2025

tinko92 May 2, 2025

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tinko92 May 3, 2025 •

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barendgehrels May 2, 2025


		[heading Description]
		[concept PolyhedralSurface..polyhedral surface]

Add geometry polyhedral surface #1402

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Add geometry polyhedral surface #1402

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vissarion commented Apr 30, 2025

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vissarion commented May 2, 2025

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tinko92 May 3, 2025 • edited Loading

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tinko92 May 3, 2025 •

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