4.3.Transfer maps

At this point the low poly version and all the high rez pieces are ready and i will continue with the uv mapping.
There are a lot of tools for UVs that you can use :UVLayout, Unfold 3D, plugins for pelt mapping etc... and some say one is better than other but i do all my uvwork with the tools built within maya, they might require more attention and planning on where to cut the UVs and sometimes will produce junk UVs but after a second trial things work well. I have tried Headus UVlayout and Unfold also but i like better the maya unfold ... works faster for me.

I won't show you how i worked on uvs because lots of the people i know don't use maya for uvmapping and most likely the information i will give will be redundant.

The idea is to unfold the uvs with little stretching ,a good hint is to keep your cuts in the less visible parts of the model(like for the arms and legs keep them on the inner part) and you could break down the uvshells accordingly to the pieces in the high rez version ( for instance boot will go as one shell , each leg as one shell etc ... )

After the UVs are done i will be ready to bake normals and other maps if necessary.

I used transfer maps tool within maya for this ( but render to texture within 3dsmax works the same way ). I will exemplify this process on the boot:

-before starting keep in mind that the uvs on the piece of geometry you are going to bake normals for should not overlap (in the end you can overlap uvs for arms or other similar objects but for accurate results move the overlapping uvs outside the 01 space or shrink them down in a corner or unused space while baking)

-import both low and high versions into maya and make sure they are on top of each other

-open the transfer maps dialog ( found in Rendering menus in Lighting/Shading-> Transfer maps... )

-select the low poly version and in the Target Meshes click on add selected , then select the high version and in the Source Meshes click add selected (see image above)
( if you do not add any geometry to the Source Meshes then maya will sample all the geo in the scene for the process )

-in the Display option for the target mesh select Envelope ( or you can select both to display both the target mesh and the envelope)

-this will create an user-editable geometry ( merely an offset of the current low poly version ) that will be used as an envelope to look for the source meshes. You can change the offset of the envelope by changing

Search envelope% slider ( or by typing a value ); the idea is that you will get better results if you will have the high rez version inside the envelope (like in the third case in the next image)

if you go too far with the offset the baking might not work properly , usually i will trial and error some values for the offset until i have most of the high rez inside the envelope like in the image below

ADVERTISE

and then select the envelope and tweak its vertices/faces/edges until the high rez will be completely inside the envelope

-then select the maps you will like to bake ;i will resume to normal map ( you could also bake ambient occlusion maps ... this way you will sample the ao from the high rez version but i did not have too much time to compute ao maps also because they require some time to render ... depending on your machine ... mine was too slow at that time for this ; instead i used Batch bake mental ray with the normal mapped low poly to bake a Final Gather pass for occlusion ... works a lot faster with comparable results... see later on for details)

also make sure you browse for a path to save the file ,select file format,map dimensions and other details you want, also make sure you set the search method to inside envelope only since the high rez will be inside the envelope

-now you are ready to render to textures and hit the Bake button

-as a note make sure to save the file before you hit the bake button because after rendering the texture maya will delete the envelope and you might need it again ( especially if you spent some time tweaking it to better enclose the high rez ) or if your map does not look ok and need to rebake make sure to undo a couple o steps until the envelope pops up in the scene again ( saving the scene is safer though :) )

-if the normal map does not look ok from the first time come back again to the transfer maps dialog and readjust some settings ( but when you have an envelope that completely encloses the high its less likely problems will occur ... you will have some hard time if the envelope intersects with the high rez ... if you are too lazy to tweak the envelope you could set the searching method to "inside then outside" or to "closest to envelope" ; there are situations when it might work and situations when you will have problems : usually you will have problems when multiple surfaces intersects on the high rez version , lets say some straps on top of the arm ... in those cases if the envelope intersects with the high geometry also then it might sample the wrong surface)

The same steps you have to follow if you are using Render to texture inside 3dsmax
-select low poly mesh go to rendering->render to texture
-check projection mapping ( to turn it on )
-push Pick and select the high rez model
-and next usually max will create a crazy envelope/cage ( autocreate process )
-select the projection modifier
-go to cage section and hit Reset to reset the cage ( the cage will fit the low poly exactly )
-in the push section you can change the Amount to offset the cage like in maya trying to enclose the high poly version
-same as in maya you can alter the cage by expanding the projection modifier and tweaking the individual elements until the whole high poly will be inside the cage
-after all the tweaking is done you select the low poly again and in Render to texture dialog you hit render
-if the map its not looking properly you might come back again and do more tweaking of the cage