Stage 1: PREPARE THE MODEL
Part A: If your model is not yet a polygonal mesh, convert it into polygons.
Part B: Checker-Letter Map: A checker map is applied to the model before unwrapping as an ongoing check on whether the mapping is stretched (resulting in rectangular checkers). Creating one ith a letter overlay in Photoshop will additionally check whether the mapping is backwards (resulting in backwards letters).
Create the 512x512 checker-letter map in Photoshop, open the Hypershade,
import the checker-letter map onto a new Lambert material and apply the material to the object.
Part C: Reference Mapping: Open up the UV Texture Editor dialogue found in the Window menu. In the face component level select the entire model and hit Automatic Mapping in the Edit Polygons/Texture menu (tear off the menu by hitting the bar at the top—we will use it a lot). Notice how the checker-letter art appears more evenly on the model and every facet of the object is now visible in the UV Texture Editor.
The UV Texture Editor includes four grid regions surrounded by empty workspace. All of your final art must fit in the upper right grid. This region is called the Zero-to-One Space, and it is all that will be exported later.
Right-click on your model in the UV Texture Editor and choose the UV component level. Select all the UV coordinates and hit [r] to sale them down to a medium-small dot. Move this dot out of the zero-one space into a light area of your checker map. The model in the Perspective Workspace should now appear this solid light color.
This is called the Reference Mapping. As each area of the model is remapped by hand, this reference mapping will disappear bit by bit. At the end it is easy to see if the artist forgot to map anything by seeing if any part of the reference map remains.
Stage 2: UVW UNWRAP THE MODEL
The model is now ready to be UVW Unwrapped. In the UV Texture Editor turn off Image/ Display Image to more easily see your work. The unwrapping process is a repeating 3 part cycle:
Part A: Face-select an area of the model.
Part B: Apply a mapping tool (either automatic mapping, cylindrical, or spherical).
Part C: Select edges and apply Move and Sew to clean up seams. UV-select the mapped coordinates and move them out of the zero-one space. This is easier to do if just one UV is selected and then Select/ Select Shell is clicked.
Wash, rinse, and repeat until the little reference map is gone. Note that whenever a face of the model is selected all the other frames in the UV Texture Editor are temporarily hidden.
Repeat the process for the door. When it is completed, select both objects in the perspective Workspace to view both maps.
Stage 3: OPTIMIZE THE UVW MAP
Before it is exported, the UVW coordinates need to be organized efficiently into the Zero-to-One space. There are four main considerations to keep in mind:
1) Fix Seams: Use the Cut UVs and the Move and Sew UVs controls on the edges to bring together the most obviously visible edges and hide seams in less visible geometry.
The most challenging technical task in painting a texture is to fix a seam in the 2D painting program. The work is much easier if the most visible edges are made seamless in the UV texture map and if breaks in the map are hidden.
The naked human arm, for example, needs two separate cylindrical maps, which should be sewn together to eliminate the seam at the elbow. Because the remaining seam down the length of the arm will be difficult to paint perfectly so that each side matches exactly, this seam should be positioned on the inside of the arm (facing the torso) where it will be less visible. In the map below the top and sides of the door are sewn to the front rather than the back as those edges are the most visible.
2) Prioritize for Important Details: Give more space in the map to areas of the model which need more texture detailed.
Areas with more important detail should take up more real estate in the final map, regardless of the true relative size. The human face, for example, is only 1/20th the surface area of the human body, but in an unwrapped figure it needs as much as 1/5th of the map to paint critical detail. In the unwrapped fridge below a disproportionately large amount of space is dedicated to the outside of the door and handle because of the magnets and papers we plan
to display there, while the inside of the door gets far less space.
3) Group by Color: areas of like color should b near each other in the map, where possible, for easier organization.
The job of the texture painter is made far easier if related areas of the model are kept together. In the human figure the pieces of the pants, shirt, shoes, hair and skin should each have their own region of the map. Note below that the pieces of the handle are kept together.
4) Optimize the Space: Reorganize the arrangement to eliminate wasted areas.
Texture map real estate is valuable. The final map size must be a factor of 2 (512x512, 1024x1024, 2048x2048, etc.) and the bigger the map the more processing is
needed to render the final image. With subtle adjustments to the position and scale of the various pieces the map can be made more efficient.
The completed UV map:
The UV Texture Editor tools
The keyboard shortcuts for the transform and workspace controls are the same in the UV Texture Editor as in the Workspace:
pan [alt]+middle mouse,
and zoom [alt]+right mouse.
The transforms work best in the UV component level. New tools of note include:
Flip Horizontally and Vertically (select on the UV Component level and apply):
Rotate UVs in increments of 45 degrees (select on the UV Component level and apply):
Cut UVs to break a seam apart (select on the edge component level and apply):
Move and Sew a seam together (select on the edge component level and apply. Use the command in the texture roll-down, not the button in the UV Texture Editor):
Selecting a shape in the UV texture editor is made easier by
selecting just a part of the UVs, holding down the [Shift] key
and right clicking on the selection to choose “To Shell”.
Notice that everything selected in the UV Texture Editor is
selected in the Perspective view. A clean and clear UV map
can work as a quick way to select various parts of the model.
Stage 4: EXPORT THE UVW MAP
Once the map is complete export the file as a JPEG. In the UV Texture Editor choose Polygons/UV Snapshot. Set the size to 512x512, set the file type to JPEG, and set the output location to your work folder.
Stage 5: PAINT THE TEXTURE MAPS
Bring the art into Photoshop (or the paint tool of your choice) and use the UV snapshot as your guide by copying it into a new file of the same size and setting it to Multiply. On a lower level, paint the art at least slightly outside the lines (the guides are typically at least a pixel of).
Create both color and alpha maps.
Alphas are grayscale maps for bump effects (white pushes out, black pushes in), specularity (white is light-reflective, black is not) and opacity (white is visible, black makes holes) as well as others (like projection and normal maps).
Hide the snapshot guides and export each file (TARGAs or TIFFs for high quality, JPEGs for speed).
Stage 6: APPLY THE TEXTURE MAPS
Import the color and alpha map files into a new BLINN or LAMBERT material in the Hypershade and middle-mouse drag the material onto your model. Hit the  key to view.
There are three render buttons on the Final Renders Status Line: Render, IPR render, and Render Globals.
The Render option is to render single frames.
IPR render allows the user to select an area of the scene to update when changes are made without having to re-render the entire scene.
The Render Globals allow the user to specify render features such as size and quality.