Retopologizing An Organic Model with ZRemesher

Retopologizing An Organic Model with ZRemesher

          In this blog post, I'm going to show the basics of retopologizing a model using the ZRemesher tool in ZBrush. Including some tricks that can be employed to tweak the topology if the initial redo isn’t quite right. This tool is capable of being used on both hard surface and organic models, but I will focus solely on what can be done to create proper retopology for organic models. ZRemesher can be used on nearly any existing model, regardless of subdivisions or how the topology is broken up. Even the mess that is Dynamesh can be corrected using this tool.

Dynamesh Head

          

          Creating the initial retopology for a model isn’t too difficult. In this example, I am using the DemoHead that can be found in the Project section of the Lightbox. I changed the model to Dynamesh, to show how the ZRemesher can clean its messy topology. To use the tool, go to the Geometry palette, click the ZRemesher section, change the settings to whatever you desire (a few of these will be explored further later in this post, to perform a few useful tricks) and then click the ZRemesher button. If there are still too many polygons, clicking the Half button and remeshing the model once more will lower the polygon count. On the other hand, if there are too few polygons and it is causing details on the model to be lost, clicking the Double button would fix this.

Retopologized Head

     

          Of course, if a higher polygon count is not wanted, the Adaptive Size could be changed to try and help the model keeps its detail. The higher the Adaptive Size is, the more flexible the topology of the model will be. Although, this comes at the cost of a higher chance of triangles being added to the mesh instead of quad polygons. Normally the default setting of 50 is perfectly fine to use, but there may be times when the model requires a higher setting to retain its shape and details. Low Adaptive settings create square polygons that are all around the same size. While a Higher Adaptive setting allows the polygons to stretch into rectangles to better fit the model’s shape, and their size will not be as consistent. Smaller ones may be created in areas where a denser mesh is deemed necessary. For example, here is the model with a much higher Adaptive mesh.

Topology with 100 Adaptive Size

          

          Another helpful tool that affects the rigidity of the model’s topology is the Curve Strength. The lower Curve Strength is, the more flexible the ZRemesher will be when creating the new topology. The higher the strength is, the curves stop being considered merely guidelines and become concrete rules. The ZRemesher Guide brush can be used to create edge loops on a model (such as around a character’s mouth) to help ensure that the topology is correct around these areas. It can also be used to fix spirals that can sometimes be found in the mesh.

          These spirals tend to appear in places such as arms, legs, and fingers because of their tubular shape. Thankfully, this can be easily remedied with the use of the ZRemesher Guide brush as well. Simply go to the Tool pallet, go to the Geometry section, click on ZRemesher, and change the Curve strength to 100. This forces ZRemesher to replace the spiral with an edge loop. However, there is a chance that creating this edge loop will cause a spiral to be created on another part of the model. Not every model is guaranteed to be able to be retopologized completely free of spirals.

Example of edge loop created by the ZRemesher Guide brush

          

          If there are certain parts of the model’s topology that needs to be fixed, Partial Mesh retopology allows these changes to be made without affecting the rest of the mesh. First, the Lasso selection tool needs to be selected, so that the area that needs to be retopologized can be isolated from the rest of the model. Make sure that the settings in the ZRemesher options are correct. If Freeze Border is being used, then the Target Polygon count does not matter as much because ZRemesher is going to have to match the border of the hidden mesh regardless. This is to be sure that the new topology merges properly with the original. Once the ZRemesher button is clicked, the model will be visible again with the new topology connected to it. For example, the Dog that can be found in the Project section of the Lightbox has double the number of polygons in its head than its body.

Example of Partial Mesh retopology

          

          In conclusion, ZRemesher is a wonderful tool to use when cleaning up the topology of a model. With helpful features that can be tweaked accordingly to get the best mesh possible for both hard surface and organic models. These are only a few of the things that can be accomplished using the ZRemesher, and it is definitely a tool worth exploring further.

Character Design and Creation - Online (Week 4)

This project focused on modeling different assets in ZBrush and Maya, ranging from complete characters to accessories for them. There were also smaller assignments that had to be completed, such as modeling hair onto premade figureheads. This was meant to help me become more familiar with the modeling process in both programs and learn what workflow works best for me.

When modeling, I discovered that using Dynamesh was the best because I could easily sculpt the characters without worrying about running out of material to work with. Honestly, this came as a surprise to me because during my first time using that modeling technique, it was nearly impossible for me to get the clay to stretch where I wanted it to. The model just looked jagged and messy. But after plenty of practice, I am now finally able to utilize ZBrush comfortably.

If I had to pinpoint something specific that did not work as well as I hoped when I was completing these projects, it would have to be when I was resurfacing the heads of my two characters. While I am proud of what I was able to accomplish, I am still aware that there are areas that could be improved on. If I had the opportunity to work on them again, there are several things that I would do differently. Such as being more careful when exporting the head of my character from ZBrush into Maya. The first time, there were appendages on the head that did not need to be resurfaced. They got in the way when I was placing polygons on the surface of the head. Having to go back into ZBrush, smooth out these unneeded details, re-export the head, and reposition it properly in Maya, took valuable time away from my modeling. Not to mention, caused me to have to alter the resurfacing that I had already completed because the scaling was slightly off. However, I learned from this mistake and did not run into this problem when working on my second head.

While I did run into several problems during the course of this project, I would not consider any of them to be more major than the others. They were all bothersome in their own right and required hard work to fix. Whenever I ran into a problem, I would adapt by investigating until I found a way to solve it. Sometimes this meant exploring the program until I figured out what tool needed to be used or what had gone wrong. Other times, I would go on to google to use forums, videos, and company websites to my advantage.

I am pleased with the end result and proud of what I was able to accomplish. Having not been comfortable at all with modeling in ZBrush when this class began, I am overjoyed that I was able to complete so many different models in the allotted time. As well as understand the program better and feel more prepared to use it in the future. However, I do know that there is plenty more for me to learn and improve on. A few examples of areas that I want to practice more are sculpting hair and working on the facial features of characters. UVing and resurfacing in Maya are also areas that I still have difficulty with. I am excited to continue honing my skills with these programs so that I can create even more models.