Re: [Flightgear-devel] nurbs headaches

2004-11-10 Thread Lee Elliott
On Tuesday 09 November 2004 15:38, Curtis L. Olson wrote: Gerhard Wesp wrote: Hmm... About what resolution are we talking here? Generally, 90m SRTM. What additional data do you have available for the runways? I guess you have it's position (two endpoints? center point, direction,

Re: [Flightgear-devel] nurbs headaches

2004-11-09 Thread Gerhard Wesp
Unfortunately DEM data is *way* too noisy and has too much potential for odd artifacts to use directly. What I have done is to take a coarse Hmm... About what resolution are we talking here? What additional data do you have available for the runways? I guess you have it's position (two

Re: [Flightgear-devel] nurbs headaches

2004-11-09 Thread Martin Spott
Gerhard Wesp wrote: What additional data do you have available for the runways? I guess you have it's position (two endpoints? center point, direction, length?) Runway center point, orientation, length, width and in rare cases an exact elevation - not to think about that the whole stuff has

Re: [Flightgear-devel] nurbs headaches

2004-11-09 Thread Curtis L. Olson
Gerhard Wesp wrote: Hmm... About what resolution are we talking here? Generally, 90m SRTM. What additional data do you have available for the runways? I guess you have it's position (two endpoints? center point, direction, length?) and ``elevation''? Commonly, the runway elevation at both

Re: [Flightgear-devel] nurbs headaches

2004-11-09 Thread Gerhard Wesp
This [wc]ould cause problems in places where runways intersect and doesn't account for the surface of all the taxiways and the rest of the Ack. I missed that point. For what it's worth, I believe I have beaten the nurbs approach into submission (mostly) and I hope that the next scenery

Re: [Flightgear-devel] nurbs headaches

2004-11-08 Thread Christian Mayer
Curtis L. Olson schrieb: I find that when I try to interpolate a nurbs surface through the grid points, the resulting surface misses many/most of the points, which is not what I expected. I also tried a least squares fit which actually I *really* like, however, I'm finding that the least

Re: [Flightgear-devel] nurbs headaches

2004-11-08 Thread Curtis L. Olson
Christian Mayer wrote: NURBS aren't good conditioned. That means that depending on the input data it can easily happen that your result will be rubbish. I'm not married to nurbs, but I'm looking for a way to fit a smooth curved surface through a set of points. The nurbs++ library is what I

RE: [Flightgear-devel] nurbs headaches

2004-11-08 Thread Norman Vine
Curtis L. Olson writes: It would be great if I didn't have to write and debug my own bezier library, are you aware of any existing code that could help me out here? Here is a classic source http://www.nar-associates.com/nurbs/c_code.html Note that you will want to repeat the edge vertices

RE: [Flightgear-devel] nurbs headaches

2004-11-08 Thread Norman Vine
Curtis L. Olson writes: It would be great if I didn't have to write and debug my own bezier library, are you aware of any existing code that could help me out here? This is another 'classic' that has source available http://eros.cagd.eas.asu.edu/~farin/cagdbook/cagdbook.html Norman

Re: [Flightgear-devel] nurbs headaches

2004-11-08 Thread Christian Mayer
Curtis L. Olson schrieb: Christian Mayer wrote: What you might try is putting a bezier patch through the points. The Bezier curve guarantees you that it won't leave the convex hull of your points. But it won't go through your controll points (what you actually want to achive to smooth your

Re: [Flightgear-devel] nurbs headaches

2004-11-08 Thread Richard Harke
On Monday 08 November 2004 13:28, Christian Mayer wrote: Curtis L. Olson schrieb: Christian Mayer wrote: Well, googling for bezier 2d gave me: http://www.cs.wpi.edu/~matt/courses/cs563/talks/surface/bez_surf.html (not exactly what you are looking for, but it looked like an easy to