Archive republication: This technical review originally appeared in Digital Production 06:2019 and was republished online in September 2021. Software behaviour, interface details and workflow recommendations reflect ZBrush 2019.
This article originally appeared in DP 06 : 2019.
Many ZBrush users are aware that it is possible to create appealing renderings with ZBrush without having to call on the help of Keyshot. Nevertheless, creating a non-realistic look was very cumbersome and limited. Until now!
With ZBrush version 2019, the preview renderer has received a very extensive update. It’s about the almost endless combination possibilities of the new NPR filters (non-photo-realistic filters). Who are these intended for? For anyone who wants to see their sculptures and models in a hand-drawn 2D style or who wants to quickly develop a wacky graphic style. This could be used in posters, comics, packaging artwork or simply as inspiration for a new design.
What are the advantages compared to Photoshop or other 2D programmes?
Because the NPR filters work with 3D data, some effects can be achieved that would be difficult to realise in a classic 2D editor such as Photoshop. The NPR system can use information directly from the 3D scene, the shape of the objects or their normal orientation, which affects the filters. The advantage of the 3D space, where you can now also set reasonable lens values for the virtual camera, is obvious. You can set up new camera perspectives in no time at all and simply press the BPR button to quickly render a new image from a different view with the set NPR filters. If you still want to continue working in another 2D image editing application, you can export your NPR rendering in individual passes such as Depth, SSS, Ambient Occlusion and other classic render passes for post-processing.
The NPR filter settings can be found in the main “Render” menu under “BPR filters”. Before you jump into the menu, which is somewhat atypical for ZBrush, you should first familiarise yourself with the dozens of NPR presets created by beta testers. These can be used to create an interesting result at the touch of a button, from which you can also make modifications. But right from the start. Position your 3D model or an arranged 3D scene in the ZBrush viewport. Play around with the newly introduced universal camera and set a dramatic camera lens, for example. Once everything is positioned, open the Spotlight browser (shortcut “,”) and search for the “Filters” tab. Here you will be offered a few dozen NPR presets.
Double-click on one of the thumbnails to activate the filter. If you are now wondering why nothing is happening, it is because you have not activated the Best Preview Render BPR. You can activate this via the Render menu, or simply press the button located in the top right-hand corner of the viewport or document window.
As already mentioned, the filters are part of the Best Preview Render Engine. Now you can simply click through the beta tester presets and the BPR will render them immediately without any further configuration. If you were to search for a new camera position and navigate in the viewport, the render would stop. As soon as you have set up a new position, press the BPR button in the right-hand corner of the viewport again. If you want to work with multiple camera settings, you can keyframe the animation as before in the ZBrush animation editor, or you can use the new Universal Camera, whose settings can be found in the Draw menu. This “real” camera was introduced in the last version of ZBrush and allows you to save multiple camera positions, jump between them and even export them to other 3D applications via FBX export.
But now let’s take a closer look at the NPR filters, how they are structured and how they can be operated.
The menu can be found under Render > BPR Filters. Basically, the whole thing is layer-based like Photoshop – but completely different. This starts with the fact that the NPR layers are arranged the other way round than the layers in Photoshop. ZBrush has twelve effect layers, which are named from F1 to F12. F1 is the lowest layer, all subsequent layers are on the previously active layer. This is a little confusing at first, but you get used to it. However, it is a pity that you cannot swap the layers using drag-and-drop to change the hierarchy as you can in Photoshop. To do this, you have to copy the properties of a layer and paste them into a new layer, then delete the original layer. However, as you are not retouching the image, this is bearable.
To get a motivating introduction to the NPR layer system, you should activate one of the beta tester filter presets from the Spotlight browser while BPR is running. They have been included to get you started and are also a good starting point for creating your own filters. Now simply deactivate one layer effect (F12 to F1) after the other. When you switch the effect layers on again (F1 to F12), you should take a closer look at the effects and their settings each time you switch them on. In the online documentation of Pixology you can find short explanations for each menu item and each slider. But the wealth of possibilities can be overwhelming at first. I would therefore like to summarise some of the BPR filter palette here to give you a better overview. The first area in the BPR filter palette deals with saving entire filters or recalling saved filters. You can also open the Spotlight browser here, which directly displays the beta tester filters. Function buttons such as Copy, Cut, Paste and Insert are used to edit the settings of individual effect layers (F1 to F12) accordingly or to transfer them to other effect layers. And the Reset Filter button resets the currently selected effect in the selected effect layer.
As in Photoshop, the F1 to F12 buttons represent the effects that build on each other. F1 is the lowest layer, each subsequent layer is above the others. Directly following the effect layers (F1 to F12) is a context menu with 46 different effects or filters, which are first rendered over the entire image. Many of these buttons are self-explanatory, but just try it out.
As with almost every image editing programme, a very long context menu deals with how the effect is offset against the underlying layers. Should the pixels be added, subtracted, multiplied or applied in one of the 30 different ways? At this point, it is advisable not to play around with too many active layers and to try things out.
The next section in the BPR filter menu deals with how strong, how transparent or how large the effect is applied. The colour for the front and back can also be roughly set here. Depending on the effect, this area changes slightly and the “Modifiers” button becomes accessible for the first time. If this can be selected, further parameters can be enabled, which can usually be used to edit the pattern and position of the effect.
If you want to bring your own texture into play, this can be done with the next menu section. If you press the large, square texture button, a window opens in which you can select the textures that were previously imported into ZBrush in the classic way. Of course, ZBrush’s own textures can also be used. The adjacent Mask Border, MBlur and MSoft sliders deal with the size of the mask, which is not created by a supplied alpha channel, but by grey scales in the texture used.
In the subsequent menu section, you can now control where exactly the effect is applied, depending on the structure and depth of the object. The Slider Mask defines the position of the layer effect based on the depth information of the ZBrush scene. In simple terms: If the value of the mask were set to -1, the effect would only occupy the background and not the object in the foreground or in 3D space. With a value of 1, the background would be unaffected.
All other sliders such as Fresnel, Shadow, AO, SSS, Depth, Cavity work in a similar way. Fine adjustments can be made using the …Exp (Exponet) next to it.
Other functions, such as influencing the direction of the normals, extend the possibilities of these new NPR filters to the extreme, but can also confuse you to the extent that all you can do is press the Reset filter button.
As a beginner, you should therefore start with just a few layers (F1 to F12) and think carefully in advance about where exactly in the 3D space or on the sculpture the effect filter will be used. For me as a character modeller, these new NPR filters are a nice gimmick – but I would recommend all illustrators, comic artists or crazy 2D artists to take a look at them, as you can get a lot more out of an existing 3D object.
