Hello,

We’re trying to make an 8x8km terrain using world composition, but are encountering a number of issues with performance. Reading through the documentation on the landscape, the recommendation is to keep the landscape component count low for better performance. But in doing this we noticed that reducing component count increases the number of triangles drawn.

From our tests we got these numbers:

[TABLE=“border: 1, cellpadding: 1, width: 900”]

Component resolution (Total)

Total components

Tiles

Triangles drawn

Total triangles

Draw primitive Calls

RAM

511 x 511 (8161 x 8161)

256 (64 x 4 tiles)

4

21.6 million

267 million

934

6.1GB

511 x 511 (8161 x 8161)

256 (16 x 16 tiles)

16

20.8 million

267 million

692

5.1GB

255 x 255 (8129 x 8129)

1024 (256 x 4 tiles)

4

7.6 million

266 million

2314

5.7GB

255 x 255 (8129 x 8129)

1024 (64 x 16 tiles)

16

7.7 million

266 million

2386

5.8GB

127 x 127 (10081 x 10081)

6400 (256 x 25 tiles)

25

2.8 million

412 million

11480

9.2 GB

The above figures were gathered for plain terrain with no material applied.

Number of total triangles was calculated using the formula: component resolution x subsection count x components in tile x tiles = total tris e.g. 511x511x4x64x4 = 267.3 million

The number of triangles drawn for each landscape was taken from start RHI with the camera positioned some 10m above terrain in a corner overlooking all of the terrain tiles.

Settings for all terrains were the same and were left at default after being imported.

So as you can see from the above table, the number of triangles drawn with the camera in the map corner was almost reversely proportional to a number of components in each tile.

For me, this was quite unexpected as I would expect the number of triangles drawn to remain the same regardless of component resolution/size especially as the size of the triangle in terrain remained the same. The only thing noticeable when viewing terrain in wireframe mode is that the density of triangles seems to remain higher in distance on a landscape with a smaller number of components. This leads me to believe that maybe a larger screen size of components works against LOD reduction in triangle count, but even so, the difference in the number of rendered triangles seems excessive.

I’ve attached screenshots of 256 component tile and 1024 component tile wire meshes. Distance in these screenshots is slightly larger from the above benchmark, so triangle count is somewhat lower when compared to values from the table.

Also, an interesting anecdote is when I load only one tile in 4033 resolution and compare the number of triangles drawn, it’s still 2x3 times higher than an example landscape of the same resolution and size found in LandscapeAutoMaterial pack.

Any help would be greatly appreciated, as we are out of ideas and getting desperate.

Thanks in advance!