This tutorial is based on the Concept Sculpting method shown in the Next Step movie. It provides a quick and easy way to build a model based on concept drawings.
1. Make sure your front and side reference images are the same scale and the images are square. Load them into the Texture palette.
2. With one of the images selected in the Texture palette, pick the Plane3D ztool and the Flat Color material, and draw on the canvas. Switch to Move or Scale mode so that the gyro appears and then scale and position the plane to one side of the canvas.
3. Snapshot the plane3D to the canvas by pressing Transform:Snapshot then move the plane to the other side. Select the other image in the Texture palette. (pic 1) Switch to Draw mode.
4. Select the White MatCap material and load the PolyCube ztool. Use the gyro to scale and position the cube over the 'front' image.
5. Press Edit ('T') to enter edit mode. Switch off Tool:Geometry:Smt and then divide the cube several times - you will need several hundred thousand polygons minimum. Switch to Move mode and click on the cube to remove the action line if there is one, then switch back to Draw mode. Select the ZProject brush in the Brush palette, switch off ZAdd and switch on RGB. Draw over the cube to transfer the image.
6. Switch off Edit and then switch on Move. Use the gyro to move the cube over the side image. Switch to Rotate to rotate the cube. Switch Edit back on, and turn on X symmetry in the Transform palette. Draw over the cube using the ZProject brush to transfer the image. (pic 2) Clear the canvas (Ctrl+N) when done.
7. Load the Polysphere ztool then append the image cube as a subtool by pressing Tool:SubTool:Append and selecting the cube from the popup. Switch on subtool transparency (press Transform:Transp) and check that the sphere and cube are aligned correctly. Press Tooleformation:Unify for each subtool if necessary. (pic 3)
8. Select the Polysphere subtool and switch to a low subdivision level. Use the Move brush to shape the sphere to fit the image outlines, being careful to keep the polygons as evenly distributed as possible. (pic 4) Switch on Polyframes if desired.
9. When the general shape is good increase the subdivision to several hundred thousand. Switch to Move mode to check there is no action line (click the sphere to get rid of it) then switch back to Draw mode. With RGB on and ZAdd off, use the ZProject brush to transfer the images to the sphere model. (pic 5)
10. Switch on Color Masking in the Brush palette. Select the Standard brush, switch on ZAdd and quickly work over the model to bring up the details. Don't use to high a Z Intensity. (pic 6, at the top of the post) Switch off Tool:Texture:Colorize to see the sculpt more clearly - the masking will remain. Finish up the sculpt by switch off the masking and detailing using different brushes and alphas.
Tip: the attached ztl has separate groups for three sides so that they can be hidden for fine detailing of the model whilst viewing the reference images.
Alternative method for the 'inside cube view', pointed out by spaceboy below: first make sure UVs are disabled (or you'll lose the polypainting), switch off Tool: Display Properties: Double, then press Tool: Display Properties: Flip to flip the normals.