On 4/29/2010 12:07 PM, David Glenn wrote: > One of the figures that I have to present to the viewer is the width & length > of the area of terrain that is covered in the window view. Back when we where > doing this in Performer, we had set zoom points, so we had an idea of the > width & length as it related to the extents of the terrain. Now I’m dealing > in a round earth that I have to factor the curve of the terrain surface and a > more dynamic zoom than I used before. Good news is that I know what’s the > altitude of the camera is from my theoretical ellipsoid at any given time. > Assuming that the terrain fallows the theoretical ellipsoid OSG has, the > camera is always pointed to some point towards the center of the earth, and > there is actual terrain under foot, is there a function that could give me > the length and width of the terrain that’s within that cameras field of view?
I'd use the LineIntersector to shoot lines out from the center of each sceen edge, and see where they hit the terrain. Then do a great-circle (or simple Cartesian if you don't care for exact accuracy) distance measurement between the left and right edge pair for the width and top/bottom pair for height. > We here have discovered that we might need to go 1Gig and beyond to get > better performance from or old Performer stuff. That means that we have to > shop for new test cards to see what works for the old Performer stuff and > keep in mind the new OSG stuff. > So one of the cards someone brought up to get is an ATI card - maybe a FireGL > card - I'm not sure! I know that most of this is going to have effect the > OpenGL side so if it works well, it will be an improvement with OSG as well > as Performer. Other than that I was wondering if there was any else that I > should be aware of. I know that I had a hard time setting up an ATI card I > had on my fedora core box – I ended up using Susi Linux, but that was the > only experience I had using ATI cards in Linux boxes. honestly, I've not found the FireGL and corresponding NVidia Quadro cards to be effectively better than a consumer-level card with equivalent specs. In the past, the FireGL or Quadro drivers are even sometimes less up to date than the "bleeding edge" consumer drivers which often had newer bug fixes. This may not be an issue now. -- Chris 'Xenon' Hanson, omo sanza lettere Xenon AlphaPixel.com PixelSense Landsat processing now available! http://www.alphapixel.com/demos/ "There is no Truth. There is only Perception. To Perceive is to Exist." - Xen _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
