Directed Study - Week 2 - Gecko

My classes are going well. It’s early in the semester and I’m already busy. I’ve gotten quite a bit of work done on my gecko character model. Working in the GDS setting has really boosted my productivity on my thesis models. The first character I’ve begun to model is my gecko. I started my work on him in Maya, and have since progressed into ZBrush. Unfortunately, I did a lot of unnecessary work in Maya. I had a plan when I was designing my gecko that I would build a base mesh for him in Maya and then export him into ZBrush and use the retopology and adaptive skin tools to create his sheet metal panels. By the time I began working on him, however, I had completely forgotten that plan… Instead, I built a solid base mesh and then started extracting faces and extruding them outward just a bit to add some thickness.

There are a few problems with this method. The first problem is that when I try to move the extruded faces to add thickness the thickness is not necessarily the same in every direction: If I pull the faces up on a surface that curves down around the side then the top part of the panel gets thickness but not the side. If I then move the faces sideways to give the side some depth, then the far edge of the top is now angled toward that side rather than remaining straight up and down. If the surface curves in yet another direction then things are further complicated… Basically, there’s quite a bit of extra work to keep the thickness of the panels equal along curving surfaces beyond just simple extruding. The second problem is that the edges of the faces I extract for the various panels all butt exactly up against one another, but I don’t need them to butt up against each other: I need them to overlap. This means that I am having to manipulate the edges even more than just the extruding process requires, because now I have to extend them in every direction to overlap where and as they should.

Doing this kind of thing in ZBrush is much quicker and produces more consistent results. If I take a base mesh built in Maya I can make a rig out of it and use ZBrush’s retopology and adaptive skin tools to create panels of equal thickness on all sides no matter how the surface curves and, in addition, all of the panels can have exactly the same thickness. (Note: It is entirely possible that there is a way to extrude evenly to a consistent thickness around multiple curving surfaces in Maya, but if it exists I don’t know it yet.) The process is as follows: Rather than extracting the faces that I need for each panel and extruding them as in Maya, I use the Maya base mesh as a rig for creating new topology but, instead of retopologizing the entire thing, I retopologize panel by panel. I basically draw a type of grid over the area where I wanted the panel (including some extra room for the panel overlaps) and then tell ZBrush to create an adaptive skin of a predetermined thickness. The program creates a piece of geometry with the set thickness that follows the surface of the rigged object (the gecko base mesh) with faces on that surface for every quadrilateral in the grid that I created. I then save that piece of geometry and move onto the next panel. I also use symmetry while retopologizing so that both sides are created exactly the same and I only have to cover half of the surface manually. Eventually, all of those different skin panels are combined as subtools in a single .ztl file where I can manipulate them in accordance with each other. I still have to do a little clean-up work on the ZBrush panels: where the overlapping portions of the panels were created the form of the base mesh was followed precisely on each piece, so I have to move the edges so that the geometry of each panel no longer permeates the space of the geometry of its neighbor. I prefer this type of clean-up work to the type that I had to do in Maya with the other process however because using the Move brush to nudge the edges of the panels in ZBrush is a much more organic process than selecting edges and vertices in Maya.


So, to recap, my gecko model creation process has gone thus so far:


I started a base mesh in Maya:

I spent a whole lot of time making panels that I’m not actually using anymore:

Then I came to my senses and finished the base mesh to ready it for export to ZBrush:

I mapped out the divisions between panels by painting on my base mesh in ZBrush:

Then I created the sheet metal panels using retopology to produce adaptive skins and combined them as subtools into a single Ztool:

Now I just have to adjust the panel edges so that the different panels’ geometry no longer penetrates that of the neighboring panels, create the base the gecko is going to be clinging to, pose the gecko, and then sculpt in the details.