Matching existing drawings to new 3D viewing angle

that sounds like a pretty intense code to make that happen. what i like to do is use landmake refrence points, and do it by hand.
this works pretty good for larger scale objects, i've never tried it on a part or small object.
for example say its a birds i view of a house.
we know:
a: wall are relatively vertical (z) axis b: horizontal lines (stucco joints, brick joints, wall breaks) are relatively horizontal (x or y) c: the image was only taken at one point.
therefore once the image is in autocad use the line command to trace a few z,x,y lines from the presepective drawing (along a roof line, floor line, wall lines, and other landmarks that can help you get orintated) then you canget your vanishing points for your perspective, there will most likely be 3.
with this information you can place the model in 3d space and overlay it to the realworld perspective. you can also pull the isometric, and orthographic views from that perspective. some information will be lost (since you can't see all the faces) however it will give you a starting point.. oh yah, you'll also need a couple dozen good measurements from the above object in order to make the scale of the image correct.
rock on

Are you looking for "Camera Match"? It will allow you to match your 3D model (say of an addition) to a photo (say of the existing building). I use 3DViz for 3D rendering at it has this function (not sure if basic AutoCad does but I'd imagine ADT does since it comes with VizRender).
To make it work with very high accuracy you need 3 points and their relationship to each other, plus the camera aperture setting.
When done right you can really make it look seamless (if the rendered materials/lighting is of an equal quality of the photo).
HTH,
Michael (LS)

If yopu know the base axis angles you should be able to set up the 3D view in AutoCAD without too much trouble. If you can set your station point accurately and know the angle you are looking at the scene from, you could use the dview command to enter the coordinate directly; better still, draw a polyline from your station point, rotate it to match the angle, move it up to eye level and then use dview to select the beginning and end points of the polyline as the locations for your view.
Marc