Imagecels: www.imagecels.com,
is a great site to search for trees, people, etc.
for Photoshop images
TreePro: www.onyxtree.com,
by Onyx, is a source for near-photorealistic trees
Viewpoint Data Labs: www.viewpoint.com,
has a vast collection of 3D models for purchase on-line.
PDF
Documents for Download
Step By Step to Seamless Textures for Rendering
- How to avoid the checkerboard effect when rendering.
Step-by-Step guide to editing texture patterns derived
from your own scanned images using Photoshop. Written
by Digital Vision.