The highest poly capital ship in vanilla sins is in the 4000-ish tri range. Frigates, and cruisers generally dont go over 2000. strike craft are around 500. Structures are up to 7000, and the starbases are in the 10,000 range.

Generally in an RTS game when there are many units on the map the saying "less is more" applys. Also you need to know that there are mesh, and texture hardcode limits. 400 meshes and 1000 textures. I dont think there are hardcodes for texture sizes, but try not to go over 2048x2048 in your texture resolution. Try to mimic how sins did its textures. 1 single -cl texture, with an associate -da, and -nm texture. It is usually best to uv-map your model on one texture sheet in this case. Will save you the headache of going over the texture limits.

https://forums.sinsofasolarempire.com/341022 may be of use, that original tutorial was kind of horrific.

Also why would you have lighting issues? Using a modified normal map as your specular map is perfectly fine, but lacking a normal map altogether seems pretty weird.

In fact the limit of the engine is around 50k triangles, not poly... and before the XSI stage, be sure to have only triangle or quad... any surface with more that 4 edges will be discarted and you will have "hole" ( can see trought the model )...

Now, 50k is a engine limit... and i assure you that you don't wish use these limit... it is good for a single ship on screen but not for fleet or battle unless you wish to kill the engine...

Personaly, i use the following limit in triangle... if you model is made of quad reduce these limit by 50%

- capitalship : 10-12k , texture 2048*2048

- frigate-cruiser : 2-4k, texture 1024*1024

- fighter/bomber : 0.5-1k, texture 512*512

contact and ask the member 'Fileosoft' about injecting the bump map into the -da. He has done that before for the Halo mod's UNSC Aegis Fate frigate. It looks the same as with a bump map (which the AF lacks), and has no wierd lighting issues.

Was working before in 1.05 but since the 1.1x version and the change in the texture system, it don't work anymore... it is why recently, i have remake the AF and the Cov assault carrier texture...

For wierd lightning issues, if it is related to shadow who jump from poly to poly, a fine tune of the red da channel help... on the modeling level, bevel hard edges help too... of calculate Normalized weighted vertex normals help too...

Like Major Stress say, experiment is a key word... one model is not the other and sins engine can react strangely to a very little change in one of the map...

By the way, never trust fully what is wrote in the .pdf from the Stardock/Ironclad mod tools... these was never updated and the info about texture are now wrong...

I've used the AF in some mods of my own, without the bump map texture, and the frigate looks just the same as when it doesn't have the texture.

Cant see the post without registering.

I do know now exactly what you did. Nice idea BTW. Would work for higher poly ships. Ill experiment with it some, and see if i can get it to work again. Though i doubt it. AFAIK Entrenchment models now must have a normal map. When i get some free time ill confirm this, or others can try this method and see if it works.

Homeworld 2 uses a similar method since it doesnt support bump maps. What it does is it uses specular mapping as sort of a "psudo bump" map. You had the same idea.  It is not exactly the same as a full bump map, but under certain lighting conditions it can fool you into thinking it is a bump map. The idea does indeed have merit. The HW2 B5 mod uses this method, and the ships look just like they do have full bump mapping. Of course they had to tweak the shaders in Maya as well. Something i have no clue how to pull off. Since i am a Max/Lightwave user. Sins is a little different. So is XSI.

Before 1.05 the Alpha Channel on the -cl texture was the specular map. They moved the specular channel to the Red Channel of the -da texture for 1.05, and entrenchment. They changed the Alpha on the -cl texture to team color. They said it was to increase the games performance. Though i noticed no increase in performance, or any drop in memory usage. Removing the normal map would increase performance, because that is one less texture a model has to load up. It would also free up a texture slot, and free up ram. Essentially killing 3 birds with one stone. I would like to see some in game screens of how you used that method.

BTW many texture artist use high poly renders of the models to texture lower poly versions of the same model