Shaders and Texturing - An Introduction to Computer Graphics for Artists - page 195

Fig. 11.15 The left side of this photo could be used as a texture map after cleaning it up but the
right side shouldn't be used as a texture because of blur

Unless you desire a special effect that requires blur, you will not want to use a map
that has been blurred. If it is a slight amount of blur and you no longer have access
to the subject, it may be worth the trouble to retouch it from the image, but usually
it isn't. To avoid blur in your texture reference photos, you should use a stable
shooting surface or tripod, your subject should be motionless, and your depth of
fi eld should be set to prevent any blur.

11.5.3.12 Occlusion

Certain subjects cannot be photographed without some other objects in the scene
blocking the view (Fig. 11.16 ). This is occlusion . If you are taking a picture of a
building, not only might pigeons get in the way, but if the building has enough deco-
rative detail, the decorations themselves may block the view of other parts of the
building. If you can avoid this by careful framing, it is worth the trouble to do so. If
a moving object like a vehicle or animal blocks your view you can take several pho-
tos. Even if the animal is in each of the photos, if its position is changed from image
to image, you can cut and paste the photos together to eliminate the occlusion.
Sometimes you will have to take separate shots from different points of view.
This can be effective if you have an immovable object in the way. If you cannot get
to the blocked material, but need it, you will have to make it up based on your best
guess from the existing reference.

11.5.3.13 Noise

If a photo is taken in low light conditions with a narrow aperture lens, it will likely
have noise imbedded in the image (Fig. 11.17 ). Noise can be very diffi cult to