How to calculate the visibility of a SurfaceImage

[zidia]

I'm showing a SurfaceImage on the ground of WW that is changing continuosly. I want to calculate in some way how much this image is visible or how much i'm close to the image. Precisly, but I think it's so difficoult to calculate, the percentuage of the visible ground that this image occupies.
I want to stop changing the image if it is not more visible or partialy visible.

I'm working at the Layer level, so I can manage the DrawingContext.

Thanks

[patmurris]

What you can try is to compute the bounding cylinder extent of your image (globe.computeBoundingCylindert(sector)) . Then, before rendering, you can test for the extent.intersect(dc.getView().getFrustum InModelCoordinates()).

[zidia]

Thank you for the replay. The solution tha you gave me is only for one problem that I had.

The second one is that I want to increase the quality of the image if i'm closer to it. The DrawContext.getVisibleSertor() gives me an approximated sector so I cannot be precise calculating the ratio between the size of the visible and image sectors.
Is there a way to calculate how much of visible terrain an image occupies?


Thanks

[patmurris]

Tiled image layers do handle the eye proximity to image tiles so as to split them when getting close enough and increase their resolution. Have a look at layers.TiledImageLayer.needToSplit(DrawC ontext, Sector).