[C5] Extra details with Displacment Shader

[Thomas]

This tutorial is currently under heavy edits! (A lot of english mistakes)

In this tutorial, you will discover how to use the displacement of Carrara, and some little tricks, to improve your render and much more! This step by step is only focused on Carrara, but also include a small Hexagon and Zbrush steps:
Hexagon was used to create the original character (you can watch the speed modelling video here) and also, to prepare the topology before exporting it to Zbrush
Zbrush was used to create the displacement map. Currently, it's the only software which allow you to create in real time such displacement maps with such details!
Carrara was finally used to generate the render, from the low polygon to high resolution render.

But first of all, what is the displacement? This features allow you to change the aspect of the geometry of your object, from a 'displacement' map, which is a simple greyscale texture (most of time, in 16bits, it's more accurate), by "pushing" the vertices of your object. It's a little bit like the bump, but in opposition to the bump, it move your topology, while bump only change the lighting aspect of your model.
Carrara also includes a "Micro displacement" which can create an extra geometry (a micro triangulation), to generate the displacement, most of the time, on the render generation.

Feel free to search over the web about displacement and microdisplacement, a lot of websites describe it and show a lot of good samples and usages!

This tutorial is only based on a "Displacement" and not "Micro displacement". And now, it's time to show how it works!

[Thomas]

First part: Modeling in Hexagon and preparing the model for the Export to Zbrush.

As explain in the introduction, the creation of the model used in the tutorial is not explain here, but you can show the video on this thread of the forum This tutorial will only focuses on one thing in Hexagon: the geometry of the object. Why? Because Zbrush, the software used for creating the displacement map only accept quadrangles (4 sides polygons) and triangles. Hexagon accept ngones and it's really easy to create such polygons in Hexagon. In fact, Zbrush can triangulate or quadrangulate the ngones on the import, but you have any control over the geometry, and if you have applied some UVs, you can be sure that they will be lost or the geometry won't be as wanted (important for animation) Below, the model in Hexagon. As you may see, it seems to have only quadrangles but it includes some ngones. Then, how to find them?

Hexagon, since 1.2 release, includes new selecting options, which are really helpful for such needs, named "Select over 4 points faces", located in the Selection menu.

Below is the result of the tool used above. As you can see, a set of polygons are selected, to show you where the ngones are located. It's not time to change this and create an appropriate geometry to create only quadrangles or triangles. But keep in mind that Zbrush, even if it accepts triangles, don't really like them, then, try to avoid them as much as possible.

And the result after some modification. Using the same selection tool won't show any 'error' and the model is ready to export.

For the export, it's important to choose the good file format. Zbrush only import OBJ and DXF. OBJ is the best format, since it keep the current topology and eventually, UVs, where DXF triangulate everything! For the export option, the default ones are ok, but if you eventually have a model with UVs, check the "Export UVs" checkbox.

Now, quit Hexagon and launch Zbrush!

[Thomas]

Second part : Zbrush displacement creation.

Please, keep in mind that this tutorial is not a tutorial about zbrush itself. It only shows the important steps in Zbrush. Please, refer to Zbrush website and forum as tutorials found all over theweb. First step is to import the OBJ model made in Hexagon. In Tool menu, click on the import button and click drag in the scene to create your object and don't forget to switch to Edit mode.

Still in the Tool panel, add UVs to your model if doesn't include them (the model of this tutorial doesn't have UVs). If your model have UVs, don't forget to do an UVcheck to see if everything is ok (Zbrush don't like overlapping UVs). The best UV mode to use is "AUVtiles" or "GUVtiles" (1) which is the mode used in the example. In the same panel, in the Morph target section, add a morph target to this model, but clicking the "StoreMT" button (2)

In the same panel, in the Geometry section, you can increase the quality of your model by smoothing it (Divide button) and start changing your model aspect and sculpt it. Feel free to use Projection Master, and others.

After some doodling, below is the result of the modifications on the original model, from two points of view.

Now, it's time to generate the displacement map, which will be used in Carrara. Go back to the first subdivision level (1) but moving the subdivision cursor to its lower value. You can notice that your model without the smoothing, si now different from the imported mesh. It's because Zbrush move the vertices of the original object, to fit as much as possible the final result If your original model need to be the same as the original (To keep skinning information, etc.) in the Morph target section, click the "Switch" (2) button to have your original model back. If you want an accurate result in Carrara, you will need the modified model generated by Zbrush. Then, don't click the "Switch" button

Below is the same model, on the left, the original (1) imported from Hexagon, and on the right (2), the same model with some vertices modified by Zbrush after the sculpting part.

Still in the Tool panel, in the displacement section, change the map resolution to a higher value. If you want the best accurate result for your displacement, you will need to have an important value. Please, keep in mind that more the value will be, more the wight of your map will be important, as the memory needed for Carrara to handle such files. 2048 is a good value. Then, hit "Create DispMap" button. If you have the Deeper plugin from Inagoni, you can also create a normal map to create a more detailed render with Carrara.

When your displacement map has been created, it has been stored in the Alpha tab. Select it and export it in TIFF format. If you have created a normal map, it was stored as a texture on your object.

Now, in the Tool panel, down all the section, open the Export one, leave the default option and export your model, in OBJ file (if you have created your UVs in Zbrush, "Txr" button must be one (default), to export the UVs too. If you have created a normal map, it as also been exported.

You can quit Zbrush and launch Carrara !

[Thomas]

Third part: Carrara and the displacement shader.

When Carrara is open, go in File>Open and choose the OBJ file format, and select your file in the system dialog box. Check the Vertex primitive radio button to create native model for the vertex modeller (keep in mind that you always have to check this option on import, which should be a default option)

Below is the model you may have in Carrara after closing the import dialog window. Double click on your model, to edit it in the vertex modelling room.

In the vertex modelling room, select your object (CTRL/Command+A) (or a simple polygon) and in the property panel, in the Model tab, change the smoothing properties: 1 - Check the Smooth radio button 2 - Change the modelling value to 1 (or you can leave it to 0) 3 - Change the rendering value to 3 (we will go back to this setting later) When done, go to the shading room, to edit this model shader.

The most important thing to do here, is to uncheck the auto update of the shader (1) (and eventually the checkboard), because the displacement shader is a processor ogre! The rendering smoothing level has been set to 3 in the modelling room and when you change a displacement setting, the render will be with a level 3 smoothing. Then, it's better to hit yourself the render button than being stop by the Carrara rendering. Switch to the displacement tab (2), this tutorial won't be based on the common shader parameters.

In the displacement shader tab, change the displacement level from "None" to "Texture Map" (1) and in the system window which popup, choose your displacement map, generated by Zbrush (not the normal map if you created one). On the map properties, swap the displacement texture vertically (2) because Zbrush swap it from the original orientation.

Select the Top displacement shader level to go back to the displacement options. 1 - Activate the displacement if it was activated before 2 - Increase the Amplitude value. From Zbrush to Carrara, a value between 2.5 and 4 is enough 3 - Click on the Render button in the preview window to have a render preview of your displaced model. Amazing, no?! 4 - Don't click the subdivision checkbox and let it inactivate. These parameters are for another kind of displacement, from object which haven't dynamical smoothing.

Go back to the modelling room and in the Subdivision section, increase the rendering to 5, to have the most accurate results. Take care, increasing this value will increase the render time! In fact, Carrara takes a long time to compute the first frame, but for an animation, this compute time is a lot shorter on the next renders.

To create more details to your model, you can also copy the displacement map in the bump channel of your shader. It can also make you avoid using a too high value for the smoothing. If you have Deeper from Inagoni, you can also use a normal map in order to a bump, the result will be a lot better!

You can now render your model. Below is an animation, showing the same displacement map, from the original model made in Hexagon, to the model modified in Zbrush (the animation was made with a Morph Target). In fact, the most accurate render is from the modified model by Zbrush, the original one have some strange distortion on the corner of the mouth.

Now, it's time for you to create your own model, with the help of Zbrush and Carrara!

[psaldari]

great!
thank you Thomas for this tutorial. In these days I was seeing like making for the displacements

Paolo

[mykyl1966]

I had to invert the displacement map as wello get it show properly.

Any ideas why?

Also I did not have to up the amplitude. I have included an example I tried here.

Cheers

Mike R

[Thomas]

The map swapped is a problem which comes from Zbrush.

[mykyl1966]

SO how do we do the micro poly displacement?

Cheers

Mike R

[Aunty Betty]

Excellant tutorial Thomas many thanks.`

May I ask what is the procedure if you wish to alter the displacement map in ZBrush at a later date?

[Teyon]

Sweet! THanks Thomas.

[Thomas]

Save your ZB tool, it will be better ;)

[Duke_of_vampires]

i hade a problem when exporting model from hex and do texture for it using project master, i think that map don't cover model right. How to solve this problem?

[Nichod]

One thing I do wish to note in regards to this tutorial is that using dynamic subdivision on all models will result in an error message and Carrara crashing. I BELIEVE this is a memory issue. Though I can't be sure.

If you come across this. The solution is to use the subdivision within the shader. And use it in conjunction with the dynamic subdivision. Watch the settings though as you can lose the definition of the model with the wrong settings.

Increase the min sample count if you have a model with lots of detail (ie. pores, etc.). Usually you can get by with a subdivision level of 3-4 in the shader and be fine. You can tweak the amplitude to bring out the definition. And increase the smoothing angle to reduce the roughness of the displacement if necessary, just make sure not to lose your details. A setting of 2-3 with dynamic subdivision should be enough.

[Nate Owens]

Ahh... a first for me.... simple success for a clueless beginner!
One tiny step on the Z-journey
Thanks, Mr. T