PFTrack 2017 Texture Maps – The Mari Workflow
PFTrack 2017 has seen a major update to it’s photogrammetry pipeline. The updated Photo Mesh node is now able to generate: Normal, Occlusion, Displacement and Colour maps; this functionality is hugely beneficial for both VFX and real time workflows. Building on the mesh simplification and texture extraction updates introduced last year, the photogrammetry toolset of PFTrack 2017 delivers first class results while allowing artists to meet restrictive polygon budgets. Also, automatically generating texture maps within PFTrack reduces the need for external applications, which speeds up your project time frame considerably.
The texture maps can be made to suit different project scenarios, for example the ‘Balanced’ colour map option can be taken if using a data set with a significant lighting or exposure disparity frame-on-frame. More detailed descriptions of texture map settings can be found in PFTrack’s reference documentation.
Normal maps can be created in either ‘Tangent’ or ‘World’ space in PFTrack. These different types refer to the type of coordinate system used while generating the map. External software does not share a common coordinate system and by including these options the range of possible workflows is extended. PFTrack uses the Mikk coordinate system, as do many real time applications. Mari does not share the Mikk coordinate system, this can be problematic if users want to export normal maps from PFTrack to Mari. This means that when generating normal maps that are intended for use in Mari, they should be set to ‘World’ and then converted using the steps outlined below.
Normal Map Steps
Create a ‘Normal’ channel by right-clicking in the ‘Channels’ window and select ‘Add Channel.’ Name the channel ‘Normal’ and set the colorspace to ‘Raw Data.’
From the newly created ‘Normal’ channel, right-click and from the ‘Import’ section of the menu select ‘Import Into Layer Stack.’ The colorspace must be set to ‘Linear.’
A new shader must now be created; from the shader menu select ‘Add New Shader’ (depicted below as the icon on the far left) and select the shader required for your project, we have used ‘Beckman’ as our example.
With the Beckman shader selected, you will see a menu containing a number of different options to set the parameters of the shader. At the top of the menu you should see a section named ‘Inputs’, from that section attach both the ‘diffuse’ and ‘Normal’ channels in their respective sections.
Making sure you have the ‘Normal’ channel selected from the ‘Channels’ menu, add a ‘World to Tangent’ adjustment layer. In essence, this adjustment layer tells Mari to take the ‘World’ coordinate system that was used generating the normal map in PFTrack and convert it to the ‘Tangent’ coordinate system used by Mari. See below, a visual representation of the normal map before the addition of the adjustment layer.
Also, make sure that ‘Flip Y’ is changed to ‘Flip’ in the adjustment layer because Mari will be interpreting the texture map as being upside down compared to PFTrack.
The image below shows the normal map converted from PFTrack’s ‘World’ setting to use Mari’s tangent coordinate system.
The other texture maps generated as part of the photogrammetry pipeline: Occlusion, Displacement and Colour; are imported into Mari in the same way as the Normal map. The remaining texture maps do not need the additional steps outlined above as there is no need to modify them to be properly used by the software. As we have previously touched upon, the reason why those additional step where required for the Normal map is due to the differing coordinate system between PFTrack and Mari.
Texture map extraction has been an incredibly significant update to PFTrack’s photogrammetry pipeline. Coupled with the updates of last year, PFTrack provides visually stunning results that can be modified to meet those all too often restrictive polygon budgets. By including variations in texture map – ‘Tangent’ or ‘World’ space normal maps for example, PFTrack 2017 is compatible with a broad range of external applications. The scope of potential workflows is greatly increased, meaning that artists of all disciplines can benefit. We have outlined the steps that are necessary to use the texture maps generated by PFTrack’s photogrammetry toolset above. To see how the toolset can benefit real time applications make sure to read the Unity workflow case study here.
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