For a system like the one illustrated in the following picture:



I am using the following code to generate rays from the camera center to each pixel on its orthogonally oriented screen:



This works well for when the camera is aligned with the world axes, ( LookVector(0,0,1); UpVector(0,1,0); RightVector(1,0,0); ) and produces the following picture:



But when I change the orientation vectors to represent a 45 degree rotation around the y axis, (i.e. LookVector(1,0,1); UpVector(0,1,0); RightVector(1,0,-1); ), it does not work as intended and produces the following aberration:



I have been banging my head against this problem all day. I've tried generating the rays with the orientation centered and then applying the appropriate rotation matrix to the direction, but I always get the same messed up result! The system seems so easy to visualise and the method I'm using seems so intuitively correct! I have no idea what I'm doing wrong. Please help.

Thank you.

Unfortunately the ray trace output is my only means of visualization.

It might be worth noting that:

when I rotate around the Look axis by 45 degrees ( LookVector(0,0,1); UpVector(1,1,0); RightVector(1,-1,0); ) I get the correct result:



but when I rotate around the Right axis by 45 degrees ( Look(0,1,1); Up(0,1,-1); Right(1,0,0); ) I get the wrong result:

Quote:Original post by knighty
Maybe it's because the camera position is too close to the view plane, so your field of view is very large. What are the values of PixelWidth, PixelHeight and CamLength?

PixelWidth = 0.001;

PixelHeight = 0.001;

CamLength = 0.1;

(ResHeight and ResWidth are 900 and 1600 respectively).

Thank you very much guys! That certainly improves matters a great deal, rotation is now working as intended. (I didn't mean to have such a large FOV btw, I had erred in my mental image of the dimensions by a factor of 10).

Now I have another headache though.

Using the method presented in the OP (with corrected FOV) the picture does not respond (well) to changes in camera position.

Using CamPos(0,0,0) gives the same result as CamPos(0,2,5) (where the triangle is at a distance of 10 and has a height of 2 and a width of 2). However, when I use CamPos(2,0,0) I get a displacement of the triangle to the left of the screen AND to the bottom of the screen...

Interestingly though, when I calculate the direction by first calculating the pixel centers with the world aligned axes, applying the appropriate rotation matrix, and then normalize(PixelCenter - CamPos), the picture responds correctly to changes in CamPos BUT I get a blank screen when CamPos.z < 0 ... which is not intended behaviour...

This is doubly puzzling to me because as far as my grasp of the geometry goes, calculating the direction using the camera orientation vectors should give the same result as rotating the pixel centers...

Any ideas?

Solved! The secondary problem of the image not responding to changes in camera position was due to a silly mistake on my part.

All is working as intended now! Thank you very much once again guys!

It's always a massive relief when you find the solution to the problem and can be once again 95% certain that you aren't going crazy and that logic is actually infallible.