Texturing for 3D
Portfolio section 1
UV mapping techniques
To demonstrate UV mapping techniques, we were asked to create a UV map for a complex polygon model. The model was an ant. The software was UV layout.
To do this, I :
1. Selected our model mesh of what we wanted to UV .
2. Used “Export selection” having changed the file type to “OBJexport” so UV Layout could read the export from Maya.
3. Saved the export file in the “scene” folder of our project.
4. Opened UV Layout.
UV layout, generally is used for organic models. Advice we were given:
• If you’re unsure about something, save a copy before using UV layout.
UV layout has a different look and feel to Maya. I found UV Layout to be quick, efficient and easy to use when you know how. Certainly it is less tedious to use than Maya’s UV Texture Editor. Keystroke shortcuts make it work.
It has three modes-
• 1st mode is a layout of UVs which you previously selected you can optimise(adjust )your UVs, similar to unfolding in Maya . It is “1” on the keyboard.
• 2nd is “2” on the keyboard and is where you can select objects of the model you want to put into mode 1 – this is also where you can go and cut up your UVs and move objects.
• 3rd mode is “3” on the keyboard, and is where to go to select the edges and the UVs you want to cut up. You can check the weighting of the UVs of your objects here, as well as check how much deformation there is on your UVs, i.e. how squashed and stretched they are.
For my ant model, I needed to cut my mesh into individual sections of ant, from the abdomen, through to the thorax and head and leg sections.
Next, I needed to make a judgement where to cut my UVs so the UV Layout program would be able to unfold it evenly, with the least distortion and without having noticeable creases in my UVs.
In UV Layout, colour is used to indicate how effective the UV application has been after the model has been cut and unwrapped. Red is where the UVs “pinch” and squash together and the blue is indicative of where the UVs have been stretched and warped. Green is good, indicating nice, even UVs.
I found the abdomen quite hard to cut. There were a lot of pieces that would overlap and required more work. The round shape required to be cut up into sections and then unfolded, before being welded together once more, to create one object as the abdomen. This gave less distortion and required fewer cuts. I kept it as one object in UV layout.
UV Layout is very user friendly by incorporating shortcuts using the keyboard and mouse-sensitive shortcuts.
When I was cutting my objects I would be in the interface 3 where you can see your model and select edges and faces.
To cut my UVs, I pressed “C” on the keyboard and at the same time selected the edge I wanted to cut with my mouse.
The edge I selected when pressing “c” would turn red and the whole row from the edge would turn yellow. I would press “W” to deselect the edges that I wanted to weld together again.
Once I had my edges I wanted to cut in red or yellow, I pressed “enter”. This would break away the edges from each other and show in the display a visible cut.
Some of the objects I could move out of the way by pressing the space bar on the keyboard in order to make cutting easier.
I selected the object by pressing “d” and this would move it to the UV display.
Pressing “1” would bring me to the UV display where I could unfold my UVs by pressing Shift”f” with my mouse over the object. I would press the space bar to terminate the unfolding.
To weld, I could press “W” to weld edges together and then press “shift “f” to unfold any distortion.
Once the UVs are ready, to put them back into Maya, it’s important to organise all the UVs either by all into one box or into separate boxes e.g. legs go with legs, hands with hands…
When packed into a box, UV Layout has an option to resize them all into one size . It tries to optimise the most number of objects that can fit into box without changing any shapes.
The illustration above shows how my ant model was packed into two red packets.