Introduction
Besides the “simple” visual quality of a texture there is one important technical aspect that defines its “quality”: resolution. This aspect results in questions each texture artist or 3D generalist at one time has: how big should my texture be? Is the higher always the better? And is there a possible link between texture resolution and image resolution?
Searching the best Resolution by Rendering
Without thinking too much we can safely assume that the resolution of your textures fully depends on the “resolution” of the image they are rendered in. In other words: the bigger the final image the higher the resolution of your texture. Therefore the important question is rather if and how the texture resolution can be linked to the final image size and where their minimum resolution limits are.
To answer this question I use a simple example/3D scene setup of the front view of a textured grid with a constant material whereas the texture has a resolution of 250×250 pixels (below image left). After the rendering of an image with the exact same size (250×250 pixels) we get this on the right:
When you compare the texture I created with the rendering on the right you can see that a lot of blurring takes place in the rendering. This is a reaction to be expected since almost anytime the virtual camera will be never be placed that perfect so the rays hit each single pixel of the texture spot on.
And of course the quality of the texture deteriorates the bigger the rendering becomes as the following image shows:
Since the renderer has to create way more pixels than the texture contains – a whooping 16 pixels for each texture pixel in the highest resolution of 1000×1000 pixels render – it has to interpolate the original material beyond anything useable (although the effect looks quite interesting).
So, since the 250 pixel texture doesn’t look that good I paint a new one, this time with a resolution of 500×500 pixels. When I now render this one with a resolution of 250 pixels, I get this result:
Compared to the original 250 pixels painting on the left, the right rendering with the 500 pixel texture looks quite nice. In fact due to the higher texture resolution the right image is even better than the left texture as the diagonals are much closer to the 1 pixel stroke and therefore much cleaner.
So, when we increase the texture resolution even further to 1000 pixels the resulting 250 rendering should be almost perfect one might think. Unfortunately (or luckily for us) this is not the case as you can see in the following image:
Instead of becoming even cleaner compared to the left painting the texture in the right rendering now starts to fade away. This result is also to be expected since during rendering at a 250 pixel resolution one ray hits 16 pixels of the texture. It is therefore logic to assume that the algorithm (in this case) increases the overall brightness of the resulting pixels. In other words: details get lost.
Conclusion
Now, with the examples above it is possible to draw the conclusion that the best resolution of a texture is the double size of the corresponding image. Or to be more precise: the final size of the corresponding object in the final image.
If you for example texture a door that will have a size of 100×300 pixels in a 2000×3000 pixels rendering, your texture should have a resolution of around 200×600 pixels. Anything below this level will cause a blur effect; anything above it will be useless at one point since the details are not “spotted” anymore by the render engine.
This fact makes our life in the big wide world of texture easier, yet it demands one essential ting: planning. For effective and efficient texturing you have to know how big each object in your final image will be and of course how big the image itself will be in the end.
But I think that this is a small price to pay for the beauty of sharp and wonderful textures…
P.S.: I have prepared a full comparison chart of all 3 textures rendered in all three resolutions. You can see it by clicking on the image below, but be warned. The image is big:
