topic Re: How can I render a polygon the contains the north pole? in .NET Maps SDK Questions

How can I render a polygon the contains the north pole?

DavidHope — Thu, 02 Feb 2017 19:44:38 GMT

The app I'm working on requires that we show the "horizon" associated with what an object (say a satellite) in space can see, based on its altitude and FOV. I typically can render this with no problem, except when the horizon circle contains the north pole, then all sorts of weirdness can happen. Here is an example:

On both the sceneview, the black outline correctly denotes what I expect to see, but the polygon doesn't fill correctly.

On the mapview, I expect to see something that looks like a sine wave filled in from the top.

In neither case did I get what I expected.

I've attached the code that generates this image. Run it and click the "Large Circle Issue" button.

Thanks,

David

Re: How can I render a polygon the contains the north pole?

MichaelBranscomb — Mon, 06 Feb 2017 21:30:42 GMT

Hi,

I've entered a bug for further investigation. Thanks for the excellent repro app.

Cheers

Mike

Re: How can I render a polygon the contains the north pole?

MichaelBranscomb — Mon, 06 Feb 2017 23:39:02 GMT

Hi David,

There is still some investigation to do, but I have observed that executing a GeometryEngine.DensifyGeodetic operation (or BufferGeodetic with 0 distance) on the geometry ("poly") helps it display as you expect in 2D. The 3D issue displaying geometries over the poles we already have logged as a bug.

Cheers

Mike

Re: How can I render a polygon the contains the north pole?

DavidHope — Tue, 07 Feb 2017 16:11:03 GMT

I tried both the DensityGeodetic and BufferGeodetic and neither helped resolve my issue in either 2D or 3D. Perhaps you could tell me where and what I should change in my code.

Also, this leads to the next problem, which I suspect may be a different symptom of the same issue.

Placing a small circle directly on the antimeridian (at 180 or -180 lon) creates the following picture:

And, even worse, when I try to draw a donut (a circle with a circle subtracted from it), I get this:

I will update the attached App. The first picture above relates to the "Small Circle Issue" button and the second to "Small Circles Issue".

David

Re: How can I render a polygon the contains the north pole?

DavidHope — Tue, 07 Feb 2017 16:22:56 GMT

Unfortunately, I was unable to replace the original attachment or add a new one.

So, I put the code out on GitHub here: GitHub - dhope1106/ArcGISRuntimeIssues: Issues as I reported them to the ArcGIS folks

I will be adding new issues as I find them.

Re: How can I render a polygon the contains the north pole?

JordanBaumgardner — Tue, 07 Feb 2017 20:36:43 GMT

We had the same issue with a line. we solved it by making a multipart polyline - the two lines terminated on the dateline. It would not be easy but you might be able to split your polygon into a multi-part polygon that used the edge of the date line as your boundary for each.

Re: How can I render a polygon the contains the north pole?

DavidHope — Tue, 07 Feb 2017 20:40:46 GMT

Jordan,

Thanks for the reply. I have considered that approach, and in one case implemented it as you suggest. However, I'd like ESRI to take a look at it and see if they can fix it before I continue pushing a workaround.

David

Re: How can I render a polygon the contains the north pole?

MichaelBranscomb — Fri, 07 Apr 2017 00:14:41 GMT

Hi,

Thanks for the updated repro. We have been investigating this: I need to try out a couple of remaining things and summarize the results of the investigation. I'll update this thread as soon as I have done that.

Cheers

Mike

Re: How can I render a polygon the contains the north pole?

DavidHope — Tue, 16 May 2017 13:53:46 GMT

Any progress?

Re: How can I render a polygon the contains the north pole?

MichaelBranscomb — Tue, 30 May 2017 18:07:58 GMT

Hi,

There are rendering issues in the SceneView with polygons that span the pole and we have a bug logged to address these. Using BufferGeodetic or EllipseGeodetic should give you the desired result for the geometry. In terms of a workaround to improve the rendering (until the rendering issues are addressed), you can set the GraphicsOverlay.RenderingMode property to RenderingMode.Static, and set a null outline on the fill symbol. That should have it looking like the example below.

Cheers

Mike

Re: How can I render a polygon the contains the north pole?

MichaelBranscomb — Mon, 12 Feb 2018 21:35:28 GMT

Hi,

We did a lot of work to improve this for the recent v100.2 release, although I think we still have some more work to do here to get it right in all scenarios.

Please download the latest Visual Studio extension from ArcGIS for Developers or update your NuGet packages via the NuGet package manager.

Cheers

Mike