advanced rendering for AutoCAD
I hate to say it, but I have never really been successful with using Walkabout to accurately match the perspective of a view of a model to the perspective of a site photo. Sorry, Ray, but it's mostly a matter of the controls -- I find AutoCAD's Full Navigation Wheel to be far more capable, intuitive, and responsive. So here is what I do in modelspace, and it works very well.
(Note that I do not use a paperspace viewport to do all this. I have found that the site photo background does not have the predictable proportions it has in modelspace. Don't know why.)
I find this method to be smooth, fast, full-screen, and free. Barring a real mathematical tool to calculate horizon lines and vanishing points, it works for me. I'd appreciate any suggestions you might have.
I totally agree with you, Bill. As an architect who have to do with building restoration, mostly, camera match is THE tool I really need to say nXt perfectly suite to me! I tried to load the model into SketchUp, make a camera match (in SketchUp is very simple and gets good results), save the view, export the model into ACAD, but the views don't correspond (don't know why!!), and nXt doesn't read views different from cameras (other issue to be solved, in my opinion).
I agree, the walkabout window is not the best tool of nXt. But you can improve the manipulation. You have to take the picture of the background you want to use, and reduce the resolution to 700x500 or something so, in the same proportion as the initial BG. Then, you use this very light image as background in the walkabout window. You can move the "increment" cursor to adjust the speed of the mouse.
You can choose any resolution you want with this slimmed-down background, for the final rendered file... And render it in tif with alpha channel, to put the real background in pshop or other.
One last advice, if the perspective doesn't match exactly to the background, no problem! In pshop, you modify your background for it match your render. And keep it so, so you can do other trials.
Xcuse my bad english!