Today we’re kicking off an ongoing series where we publish interesting and useful support cases. We’re calling this Support Diaries.
This time we cover a couple of options for architectural visualization workflows. The question is: how to get the benefits of Terragen’s atmosphere and lighting realism with the interior rendering quality of more general purpose systems like Vray, Arnold, or Indigo Render. Let’s dive right into our suggestions (and thanks to David for the interest that inspired this post)…
…I’d like to dive into workflow that could give you the results you’re looking for, but first I want to establish a clear and honest baseline. Our renderer is optimized for large-scale outdoor scenes and I think you will find it disappointing in comparison to Vray, Indigo, and others for interior rendering. This is where path tracing and other more “brute force” global illumination systems excel and where our renderer tends to do less well. We are working on improvements that will make Terragen more suitable for interior as well as exterior rendering, but for now I think you will have to accept rendering of at least your interior environments in another package.
Update: as of mid-2019 and version 4.4, Terragen now has an effective and capable path tracing render mode built-in. It can provide good quality, realistically-lit rendering of architectural models and much more. Try it out as an alternative to the below workflow!
Now, with that in mind, let’s look at two possible workflows. The first is as you describe, importing your models into Terragen and doing exterior renders (given the assumption that interior renders still need to be done in some other program). Unfortunately we do not currently support FBX 3D model import, FBX import only handles camera, lighting, and animation data, not geometry. You can however import OBJ format models with image-based textures or simple material color assignments. I have actually worked with Sketchup a little bit myself and was able to export OBJ to use in Terragen, but the compatibility depends in part on how you have constructed and textured your 3D models. In some cases it is beneficial to pass your exported model through a 3rd party 3D model adjustment application like PoseRay (free).
In any case, assuming you can get your model and textures into Terragen successfully, you can then add bushes, trees, and other environmental elements, set your sun position, add clouds, etc. for your realistic renders. This is a valid workflow, especially once you establish best practices for model construction and texturing and get your export workflow solidified. Depending on your overall needs (for example whether exterior renders are a large or small part of your output needs), this may be a worthwhile thing to develop.
However, another approach to consider is simply using Terragen for background and lighting and handle primary rendering in another package. Consider that atmospheric scattering primarily has noticeable effects at larger distances. This means that you can setup your overall environment – background hills/mountains, atmosphere, clouds, lighting (sun), etc. and render it in Terragen, saving it as a spherical environment map in high dynamic range (EXR format). You can then use this for Image Based Lighting (IBL) in any other capable renderer and you should get a good approximation of the realism of Terragen, but on a smaller scale and also for interior renders. As long as the lighting model is setup properly, with your Terragen environment image providing primary lighting, then for interior or exterior renders you will have good realism from any respectable renderer.
Handling the intersection of the background Terragen render and foreground elements could be a challenge, depending on the angle of your shots, whether you need animation (and if so, how large your camera moves are), and other factors. But there are a number of things you can do to effectively blend foreground and background elements, including using the same 3D model resources (e.g. grass and bush models) in both packages, hiding the borders of your foreground landscape with trees, other buildings, etc., or using specific camera angles to avoid a focus on such border areas.I think your simplest workflow option, and the most flexible, is probably to use Terragen to render out environment maps. So I think it makes sense to start there. You might still want to export your 3D models to use for basic scene matching and lighting development in Terragen, and in so doing you might learn enough about the workflow to enable more rendering directly in Terragen. But to start with I think you’ll finalize your lighting by rendering it out to a spherical EXR image and from then on you benefit from any rendering capabilities of your chosen renderer/package. Note that you would need Terragen 4 Professional for spherical camera output and EXR support for this workflow.
Conclusion: if you are new to Terragen and wanting to incorporate it into an Archviz workflow, start by outputting spherical, high dynamic range environment maps from Terragen and use them for Image Based Lighting in your primary package/renderer. This should give you the realism of lighting and large-scale atmosphere that Terragen is known for, while maintaining familiarity and interior rendering quality that other software excels at. You’ll need Terragen Professional for the spherical camera and EXR output capabilities. You can apply for an evaluation license of the Professional version by just filling out this form.
In the future we aim to improve interior rendering in Terragen so that it is more of an all-in-one Archviz solution.