Hey Brian, that's a superbly detailed 'picture' of how you go about it and a very good guide for anyone considering how to change photos into Intarsia patterns. I could picture every move you are making and it sounds facinating,
This should form the start of 'How To' sections of the forum on Intarsia so that it can be made available to all. Any additional ideas can be added from time to time and an Intarsia instructions is born.
In the photo, the front wheel is being trned to the right and if I've understood correctly, the drivers right hand and the front wheel tyre would be highest points. From a 1" start down to 1/4" does not give a lot of variable depth, so it could be that those initial areas are even raised further to allow more depth?
Thanks for the lesson, but I can only count it as lesson 1, with more to follow please.
Malcolm