retopology

Retopology tools in Modo by Xuan Prada

A few months ago I wrote a post about retopology tools in Maya. I'm not using those tools anymore, now I deal with retopology using Modo.
I'm doing a lot of retopo these days working with 3D scanners and decimated Zbrush models coming from the art department.

Pretty much all the 3D packages these days have similar retopology tools, but working with Modo I feel more freedom and I work more comfortable doing this kind of task.

These are the tools that I usually use.

  • Before starting I like to set the 3D scanner as "static mesh". Doing this I will hide all the item's components making this process much easier.
  • Pen tool: I use this tool to draw my first polygon. That's it, after drawing the firs poly face I drop the tool and don't use it anymore.
  • The type of geo should be polygon and make sure the option "make quads" is activated.
  • As I said, I draw just one face and drop the tool.

To carry on with retopology I use the "topology pen tool" which combines all the other retopology options. I use this tool to make 90% of the work.

These are some of it's options.

  • LMB: Move vertex, edges and faces.
  • Shift+LMB & drag edges: Extrude edges.
  • Shift+LMB & drag points: Create faces.
  • Shift+RMB & drag edges: Extrude edge loops.
  • RMB & drag edges: Move edge loops.
  • CTRL+MMB: Delete components. (faces, edges y vertex).
  • Inner snap: This option allows you to weld interior vertex.
  • Sculpt -> smooth: Allows you to relax the geometry, very useful to make a better distributions of the edge loops.
  • If you work with symmetry you probably want to align the middle points to the center of the world.
  • In order to do so, select all of them and go to vertex -> set position.
  • Then you can assign a common values for all of them.
  • To create the mirror press "shift+v".
  • To merge both parts just select both items, RMB and click on merge meshes.
  • Once merged just select the points and go to vertex -> merge to weld them.
  • Topology sketch tool: Allows you to draw polygons very quick.
  • Contour tool: Allows you to draw curves that will be connected using the bridge option. Very useful for kinda cylinder parts like arms or legs.
  • Obviously if you draw more curves you will get more resolution to match the 3D scanner.
  • You can create a very quick geometry and then add resolution using the "topology pen tool".

Quick Lidar processing by Xuan Prada

Processing Lidar scans to be used in production is a very tedious task, specially when working on big environments, generating huge point clouds with millions of polygons. That’s so complicated to move in any 3D viewport.

To clean those point clouds the best tools usually are the ones that the 3D scans manufacturers ship with their products. But sometimes they are quite complex and not artist friendly.
And also most of the time we receive the Lidar from on-set workers and we don’t have access to those tools, so we have to use mainstream software to deal with this task.

If we are talking about very complex Lidar, we will have to spend a good time to clean it. But if we are dealing with simple Lidar of small environments, props or characters, we can clean them quite easily using MeshLab or Zbrush.

  • Import your Lidar in MeshLab. It can read the most common Lidar formats.
  • This Lidar has around 30 M polys. If we zoom in we can see how good it looks.
  • The best option to reduce the amount of geo is called Remeshing, Simplification and Reconstruction -> Quadric Edge Collapse Decimation.
  • We can play with Percentage reduction. If we use 0.5 the mesh will be reduced to 50% and so on.
  • After a few minutes (so fast) we will get the new geo reduced down to 3 M polys.
  • Then you can export it as .obj and open it in any other program, in this case Nuke.

Another alternative to MeshLab is Zbrush. But the problem with Zbrush is the memory limitation. Lidar are a very big point clouds and Zbrush doesn’t manage the memory very well.
But you can combine MeshLab and Zbrush to process your Lidar’s.

  • Try to import your Lidar en Zbrush. If you get an error try this.
  • Open Zbrush as Administrator, and then increase the amount of memory used by the software.
  • I’m importing now a Lidar processed in MeshLab with 3 M polys.
  • Go to Zplugin -> Decimation Master to reduce the number of polys. Just introduce a value in the percentage field. This will generate a new model based on that value against the original mesh.
  • Then click on Pre-Process Current. This will take a while according with how complex is the Lidar and your computer capabilities.
  • Once finished click on Decimate Current.
  • Once finished you will get a new mesh with 10% polys of the original mesh.

Retopology tools in Maya 2014 by Xuan Prada

These days we use a lot of 3D scans in VFX productions.
They are very useful, the got a lot of detail and we can use them for different purposes. 3D scans are great.

But obviously, a 3D scan needs to be processed in so many ways, depending on the use you are looking for. It can be used for modelling reference, for displacement extraction, for colour and surface properties references, etc.

One of the most common uses, is as base for modelling tasks.
If so, you would need to retopologize the scan to convert it in a proper 3D model, ready to be mapped, textured and so on.

In Maya 2014 we have a few tools that are great and easy to use.
I’ve been using them for quite a while now while processing my 3D scans, so let me explain to you which tools I do use and how I use them.

  • In this 3D scan you can see the amount of nice details.  They are very useful for a lot of different tasks.
  • But if you check the actual topology you will realize is quite useless at this point in time.
  • Create a new layer and put inside the 3D scan.
  • Activate the reference option, so we can’t select the 3D scan in viewport, which is quite handy.
  • In the snap options, select the 3D scan as Live Surface.
  • Enable the modelling kit.
  • Use live surface as transform constraints.
  • This will help us to stick the new geometry on top of the 3D scan with total precision.
  • Use the Quad Draw tool to draw polygons.
  • You will need 4 points to create a polygon face.
  • Once you have 4 pints, click on shift yo see (preview) the actual polygon.
  • Shift click will create the polygon face.
  • Draw as many polygons as you need.
  • LMB to create points. MMB to move points/edges/polys. CTRL+LMB to delete points/edges/polys.
  • CTRL+MMB to move edge loops.
  • If you want to extrude edges, just select one and CTRL+SHIFT+LMB and drag to a desired direction.
  • To add edge loops SHIFT+LMB.
  • To add edge loops in the exact center SHIFT+MMB.
  • To draw polygons on the fly, click CTRL+SHIFT+LMB and draw in any direction.
  • To change the size of the polygons CTRL+SHIFT+MMB.
  • To fill an empty space with a new polygon click on SHIFT+LMB.
  • To weld points CTRL+MMB.
  • If you need to do retopology for cylindrical, tubular or similar surfaces, is even easier and faster.
  • Just create a volume big enough to contain the reference model.
  • Then go to Modeling Toolkit, edit -> Shrinkwrap Selection.
  • The new geometry will stick on to the 3D scan.
  • The new topology will be clean, but maybe you were hoping for something more tidy and organize.
  • No problem, just select the quad draw. By default the relax tool is activated. Paint wherever needed and voila, clean and tidy geometry followinf the 3D scan.