Is tessellation/displacement mapping ever worth it?

So I’ve gotten around to playing with the tessellation settings in UE4 and I have to admit, it’s not as resource hungry as I first thought it would be.

However it made me think, is it really practical to use?

The whole purpose of tessellation is to increase polycount, but for the resources it costs, why not just model a higher poly object instead?

For example, take a standard Fire Hydrant (what I was using to test with). The low poly mesh is 1,300 polygons and the high poly is 40,000 polygons. Now, you could just apply a couple of tessellation multiplers on it. But at the cost of one hydrant, why not just model a 5,000 poly hydrant instead and spread them throughout a level?

Same goes for displacement mapping. You could tessellate the ocean, or why not just make the ocean higher poly to begin with?

If I had to imagine a practical scenario for tessellation, it would have to be in a very linear/corridor like game. Trying to model something like individual bricks on a house, or stone pavement would be much more easier using a displacement modifier and since the level is so small, you will recognize those details.

I also think another huge problem with tessellation is animation. At least static objects will always remain still and thus require less processing cycles. But actual human characters will need to move and express themselves.

Basically the reason is that it only increases the poly count when you are close to the object, so as you zoom in the tessellation multiplies. Same with a 5000 poly model, tessellation will increase the poly count as well the closer you get to the object. Have a look in my signature for a link to 2 videos which show the effect in lit mode & wireframe, it simply adds more vertices to areas closer to the camera, and moves with the camera, therefor you get the best quality in a smaller area instead of doing the whole mesh at high detail, which can minimize the performance hit.

Hope that helps (and makes sense)! :slight_smile: