CAP 161 - Digital Imaging for Animation

Lesson 3 - Prepping for Texture Creation


This lesson covers material in chapter 4. Objectives important to this lesson:

  1. Gathering, preparing, storing
  2. Photography tips
  3. Sources for textures
  4. Tips on preparing textures
  5. Tips on Photoshop tools
  6. Exercises

This chapter begins with an overview of the topics. General advice: save all the images you can, you may want them later. The author defines a resource as any digital image that helps you create your art. (page 132) This includes photos, scans, images that inspire you to do something, and more. The author recommends getting a large hard drive to store your resources on, which is good advice for anyone who works on a computer.

The author discusses creating original art from scratch in Photoshop, which is the most likely method of avoiding unauthorized use of someone else's art. Note that I did not say it was a sure way. It is still possible to create derivative art if you are basing your art too closely on someone else's.

A variation that the author discusses for several pages is taking digital photos of interesting source material, and using them either as references when you create art, or using them as source material to manipulate in layers in Photoshop. He makes a point with the images on pages 138 and 139 that an image can become something new when used as a part of a new texture. Look at the image of the hair dryer intake vent on page 138, and compare it to the "sewer grate" on the same page. You can see that the art was based on the original image, but enough has been changed to make it look more solid, more weathered, more like the end result the author wanted.

The author provides some general tips on taking photos that will be texture resources:

  • take pictures in large resolution, to get as much detail as possible - once the picture is taken, you may not be able to take it again
  • take the picture with the image lined up squarely in the frame - look at the image on page 140 to see why it would be easier to work with an image of a brick wall that is square in the frame, as opposed to tilted at an odd angle
  • get the picture you want - note the images at the top of page 141 which show objects in the same frame that are in and out of focus
  • avoid using a camera whose lens distorts the image, as shown on page 142
  • take pictures on a cloudy day - the author reminds us that photographers who are going for pretty pictures like to use diffuse light near sunrise and sunset, but texture photos often look better later in the day when clouds diffuse the light without changing its color
  • avoid distortion from bad camera angles - this may not be possible for some shots, such as the window on the upper right corner of page 144 (a possible fix for that is offered shortly)
  • don't use a flash if you can avoid it - the flash will change the image you are trying to capture at best, and may add an unnatural light to the image, as shown on page 148
  • plan for an alpha channel - look at the image on page 149 of the tree, and think about what the photographer might have done to remove the grass and sand (background) from the photo before it was taken
  • scan objects when necessary, but use digital photos instead when you can

The author recognizes that you can buy collections of digital images that may be of some use, but he recommends not using them unless you change them significantly. He recommends not using stock game art because it has all been used before. He recommends not using photos from collections of pretty photos, because they typically do not have interesting textures in them. He does recommend collections of textures, but recommends more strongly gathering your own image resources, swapping with friends who get their own as well, and always compositing and modifying to create a new end result in Photoshop.

The author is a little vague in his discussion of looking for images on the Internet. He points out that they are often low resolution images, and that they are often copyrighted. The second issue is more of a problem for most students who have not been taught to keep their hands off someone else's work, even if it is posted on the Internet. In general, look on the Internet for information, for references, for inspiration, but not for free art. If you are researching what something looks like, fine, look it up. And when you find it, make your own image based on the information you found.

The author briefly discusses using a 3D modeling program, like 3DS Max, to model an object and to render an image of it. His focus in this book is using Photoshop, so he does not go into detail about this method. We will cover it with a bit more depth in this class, and will cover it again in the next six classes in this curriculum.

On page 152, the author turns to things you can do in Photoshop to clean up digital images and get them ready to use. He talks about several uses of the Crop tool, warning us first that the use of the Crop tool is generally permanent: you can't reverse it. For this reason, and many others, never modify your only copy of any file.

  • crop in a square - hold down the shift key while you crop to force it to crop a square area
  • crop from the center - hold down the alt key while you crop
  • change the crop tool mouse pointer - use Caps Lock to change the mouse pointer to cross hairs
  • fix perspective - this applies to the images you have to capture at a bad angle: illustrated on page 155, draw a crop box, check the Perspective box in the Options bar, drag the corners of the crop box to the corners of the image you want to keep, and press enter to get a squared off version of the image
  • resize the image to match another image - the text calls this resampling, and it is described on page 154
  • trim transparent pixels - as shown on page 156, the trim command will remove most of the transparent pixels from an image

Page 157 illustrates the effects possible with the Free Transform tool. The author explains that you may have to reshape an image a lot to get it in shape to work with another image. Be advised that you can use this tool to make an image bigger, but that will not increase the pixel depth of the image. It will try to interpolate pixels, guessing what the missing pixels might look like, and putting those guesses in place in the image.

Tutorial 4-1, Tiling Stones: The author discusses tiling images for several pages, and you should look over this material, but it will be clearer once you start the tutorials that begin on page 169. This tutorial continues through page 179. Carry out all the steps, and make sure to save your work incrementally. Show me your work periodically through the lesson.

Useful Information:

  • The source file for this project is under Project Images\CH_004\edge_copy_tiling. It is the only jpg file in that folder. It does not match the one in the text exactly.
  • In the Setting Up the Image section, refer to the picture on page 172. The grid settings should be Gridline every 128 pixels. Subdivisions should be 1.
  • If you do not see the grid, open the View menu, hover over Show, and select Grid. If you do not see the rulers, which you need to see to drag down a guide, select View, Rulers.

  • In the Cleaning up the Image section, find the High Pass filter under Filters, Other, High Pass. Try various settings for the filter. I thought 30 pixels was about right.

  • In the Copy and Crop Parts section, you may need to change the snap settings under View, Snap to...
  • The text does not tell you to use the High Pass filter again on each new piece as you paste it into a new layer. Use it this way, or the pasted sections will not match at all.

  • In the Removing the Seams section, after you flatten the image and crop it, use ctrl-A to select all before engaging the Offset filter.
  • When the Offset filter dialog box is open, try several different values for the Horizontal and Vertical settings to make your image unique to you, and to find a version with fewer problems to correct in the next section.

Crop Tool Exercise

We will also do an exercise in class to practice using the crop tool to correct a bad camera angle.