The z coordinate of SurfacePolygons

[Denis]

Hi,

I want to render a lot of polygons (>10,000), and I have tried using the render.Polygon, as well as render.airspace.Polygon to do this, but they seem to take some time to complete the rendering.

I started to look at render.SurfacePolygons, and notice it can render the polygons faster than previous two approaches. Since the polygons need to be slightly above the ground, I wonder if there is a way I can set the z coordinate when using the SurfacePolygons?

Thanks,
Denis

[BuM]

Hi there,

it is not possible to give SurfacePolygons a height coordinate, because SurfacePolygons are not 3D objects in the scenery, but Textures on the surface of the earth. Thus, to elevate SurfacePolygons, you would need to elevate the whole surface that they are drawn onto.

What might be possible however, is to have an extra layer similar to the earth layer, but without map data (meaning fully transparent) and with a higher altitude than the earth layer. Drawing your SurfacePolygons onto this layer might give the impression of elevated SurfacePolygons. Never tried such a thing, though.

However, I reckon that your solution probably lies in some way to render 3D Polygons more quickly some way.

[Denis]

Thanks BuM,

I see what you mean. Regarding to the the extra layer you mention, do you have any suggestion of layer one to use, as I couldn't find one in the package that allows you set the altitude?

Thanks,
Denis

[BuM]

Sorry, I have not done much with the map layers. I would suggest finding out, which layer displays the current world, then override this class leaving out all the image loading.
The height of the terrain is specified by a height model assigned to the layer, afaik.
Still I do not know how to tell WorldWind to render SurfaceObjects onto the extra terrain layer instead of the normal one. Maybe this idea draws too far, hopefully someone else has a better idea in one or another direction.

[tag]

SurfacePolygons are rendered on the terrain and cannot have an altitude.

There is only one terrain instance and it's not associated with any layer. Earth is not a layer but a Globe with an elevation model. You can have multiple or replacement elevation models, but it won't have any effect on SurfacePolygon because all elevation models are combined to form the terrain.