Why are tracks so......

T

TheCowboy

Steam is King
Could someone please explain why tracks can be so bad on frame rates?

I decided I needed a short break from modeling and started a layout designed for operating big steam locos. The layout is set in 1940-early 1950s era. I have built a small town complete with streets, trees and most of the details need to make it look somewhat realistic.

Picture 1
The small town with the station and some tracks in the forground. Framerate on this picture 24-26.
Picture 2
The other side of the tracks showing a very small 2 track yard and loco servicing facilites with 4 tracks leading to the coal tower (and I am not even done over here with the details) and the framerate on this picture about 14-15.

As you can see, there is practically nothing in this picture as far as structures, its basically track. I had 2 more tracks here and my framerates were down around 11-13, which is absolutly unaccepatable, so I deleted 2 of them.

Again, my question, why are tracks, which I thought were low poly items, so bad on framerates.

Any input would be greatly appreciated.
Thanks
 
Prepare yourself for a

COMPLETELY UNEDUCATED GUESS!

Could it be because the splines are poly weighed by sections, and the track sections are so short (compared to other splines) before they have to repeat, there ends up being many more sections in a shorter distance?

Ed:confused:
 
Another COMPLETELY UNEDUCATED GUESS!

It could also be because the spline points are too long? I've found that splines (track or not) that stretch over the length of a baseboard, or a multiple extra-long ones can slow down the FPS.
confused.gif


Not saying Euphod is wrong or anything! Just from personal experience.
 
Also, check if the track is 'chunky-mesh' or not. If it is 'chunky-mesh' track then you will see a fairly low performance loss from it. However 'modeled' track (Even in the same shape as 'chunky-mesh' track) will give poorer performance. If you are using this track, or the higher detail tracks that are available, check to see if there are different length versions available. Most of the high detail tracks come in 2m, 4m, 8m, and 16m (Or similar) lengths. This helps to control the performance hit.
Zec
 
Eds 100% correct. If you've make a track spline then you know that your track is made from 1 mesh that usually is 2,4,5,6 or 8 meters long. (could be more or less) For this example lets say that the track segment is 100 polys for a 5 meter long segment. As you stretch out your track spline the Trainz program will stretch or compress that segment to a point untill it adds or removes another segment. So if you stretch out the spilne 100 meters you should have about 200 segments at 100 polys each. Now you have 2,000 polys instead of 100. Now stretch it out to 1,000 meters. You will now have about 2,000 segments totaling 20,000 polys. Now make that a 4 track yard. Now you have 8,000 segments at 80,000 polys. You should be getting the idea now. That's without any rolling stock or scenery items. Adds up fast don't it.
Then like Zec said. With chunky mesh it will limit this problem.

Bill
 
Last edited:
never thought of them that way, but it makes sense. and if they were not short, the track would look veryy bad, and kinked
 
TheCowboy, Is your graphic card are too old for this?
Try Ati Radeon Xpress 1600 for great perfomance!
 
colhad said:
Nup, your wrong, now sit down and shuddup!!!:confused:
Click to expand...

Fame is so fleeting.....

So, then if you made fixed track that rendered as poorly as built in spline track, could it possibly get better frame rates? What about just using the spline rails over a texture of the ties/sleepers?

Ed
 
So some track is better than others. Might be helpful to have a couple of suggested kuids posted. Given the choice of 2m, 4m, 8m, and 16m do I assume it's better to lay the 16m version for frame rates?

Thanks John
 
For me personally, I'd gladly sacrifice FPS for good looking track. I'd rather that than use that pathetic old built-in Auran track.

The suggestions about the lengths is correct, I use the shorter sections for turnouts and crossovers etc, and the long ones for general mainline, probably 8m sections are acceptable.
 
There was a track test that was mentioned on the old forum. Basically, you take a clean baseboard and with FRAPs or Game Recorder running,
1 - you note your base FPS on the baseboard.
2 - lay out a section of track, note FPS.
3 - Repeat #2 for every track you have.

When I did it in 04 on my previous computer, chunky track came out better than modeled. And 4m meter worked better than 2 meter of the same track. Never heard of anything bigger than 4 meter.

Course, I should mention I then got the new computer when the old one died and all the track came up the same, that might be an 04 thing because my base FPS in TC is much better than 04 by almost twice as much.
 
This may or may not help but I ran into a frame rate problem on a downloaded map, it ran fast until I downloaded some of the missing content. I found out it was the signals had missing coronas and made a 10-15 fps deference.
 
Euphod said:
I'M RIGHT?! IN YOUR FACE!
(*Get's up....does a victory dance...picks up mouse and spikes it to floor.)

crap........

Ed:eek:
Click to expand...
ROFL. :hehe:You something else Ed. Just don't forget to pick that mouse up before the cat gets it.

Something to consider if you don't want to use the chunky mesh track is to use the longest segments you can on your curves and still keep a decent looking curve then use the longest spline segment track on the straits. From past experiance 4 meter works on most curves then 8 + on the strait sections. If your making a yard with 4 or more tracks your still better off using chunky mesh track unless you have a very high end computer.

Bill
 
Given the choice of 2m, 4m, 8m, and 16m do I assume it's better to lay the 16m version for frame rates?
Click to expand...
Yes, use the longest you can without getting a jagged look to the rails on curves. Personally I tend to get lazy and stop switching back and forth at every curve, but it will help.

I might point out that this does not apply to fully modelled track where the ties and perhaps tie plates and spikes are modelled. In that case the longer section has almost as many polys as the short section repeated.

As I understand how it works, all chunky mesh track is the same at 2 polys per section, the variable being the size of the graphic image being mapped onto the plane of the track. If you are comparing two chunky mesh tracks, look at the size and number of the associated tga's or bmp's...smaller is better, at least as far as FPS.
 
Thanks for the info guys.

I came home this evening and looked at the track I had used. It was not a chunkey mesh track and came in 2,4,8 and 16 m segments. In setting up the yard I had not paid that close attention to the pieces and had laid the 4 m segments on the long straigt sections of track and 2 and 4m segments on the curves. Well I went back deleted the 4m segments and replaced them with 16m segments. WOW...... I placed the camera in nearly the same view that I took the second picture last night and 33 fps!!!!

I will pay much more close attention to what I am doing with track in the future.
Shane

Now for a little more education please.....chunky mesh. I have heard the term, read a little about it in the CCG, but I guess I dont understand how you can get a 3d track out of 2 planes per segment!?! And why would you not use chunky mesh all the time other than if you wanted really detailed track that showed actual fish plates, bolts, spikes, ties and other details (which most of us know will kill frame rates), because as far as I can tell, there seems to not be that much difference in the track I used above and a chuncky mesh track that I put down for the mainline as far as details go. Can someone educate us a little more on this subject please.
 
I would suggest laying the longest lengths you can, then go back and replace the bits with shorter lengths where you see jaggies round curves etc.

We would all like to lay high detail track, with all the ties, bolts, fishplates etc, but it does kill the framerate.

Some suggestions I have used is to use the above and/or use mesh reducing track or LOD. MRT does have some drawbacks however (getting a smooth transition from detailed to lo poly is one, moire fringes is another)

Its all a compromise, but select a method that suits you, the layout and your potential customers (free or pay). Try to model with the lowest denominator, otherwise you are forcing Trainzers to buy a new computer rather than paying Auran for new updated versions (they need the money).

Your case below probably refers to a 3 or 4 track scene, try the same with a 40 track yard, that will sort the men fro the boys so to speak.

I do my track tests with 60 tracks yard, 200 cars/locos, then judge the difference between track types.

Chunky mesh is an 'in between' of V low poly (6 poly per segment) and super detailed track like you mention (sometimes 500 poly per segment). Chunky should be 18 poly per segment or thereabouts. Length of segment is important too, as is bendy or not.
 
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