I think you can do this: 1- Render the background in Bryce and save the image. 2- Import the eagles in Bryce with the same background, render it and save the image, then do a "Mask render of the eagles" and save the image.(I dont understand why you cant rotate tha eagles in Bryce) 3- In photoshop load the bacground, then load the eagles, and then load the mask image, use the mask image for "mask" the eagles, then select the eagles layer and invert the mask, hit delete and the backgroung of the eagles layer will dissapear, I think thats all. If you dont understand is because my poor english.