Is there a practical limit to number of baseboards using HD Terrain


Train Enthusiast
Is there a practical limit to the number of baseboards that can be used in routes using HD Terrain? I know the file size is much larger than just using the 10m grid size. Is there a size limit on how big a cdp can be? I have converted several of my existing routes and saved them all without problem. But they are all less then 700 baseboards.

I wondered the same thing when I converted my large route I started back in the TRS2004 days to HD and the route went from 334 MB to over 2 GB!

With that in mind, an exported route will be compressed to half that size when exported to a .cdp file. I'm not sure what the exact size limit is with a .cdp file and I'm afraid we'll reach the file-size limit for that format. The issue is that we can write large .cdp files but they can't be imported again. I ran into this with TS12 and with T:ANE. T:ANE was a bit more forgiving but TS12 Content Manager crashed to the desktop in seconds of barely ingesting the file. That file was about 750 MB at the time.

Knowing the exact size limit will help, but do you want to cut your route apart to save it in order to be able to import it later? This would surely be very inconvenient and really inefficient.

I use .cdp files all the time as interim route backups and for final route backups. The interim backup is used for when I'm going to merge or do other drastic changes to an existing route and the just in case backup has come in handy more than once. Needing to restore the two parts separately as two routes and then merging them back together will definitely be more than annoying.
If you have patched your copy of TRS22 to the latest beta patch, you could try importing the HD route into it to see what happens. I've played around just a tiny amount with that but I don't have any route cdps that big.
I use cdp files to backup individual routes all the time and use these backup files to transfer the route to another install, either on the same computer or another one. I of course do a complete backup on a regular basis. So far I have not run into an issue where my HD routes have crashed my CM because of file size.

Breaking a route into separate parts in order to import it to another install and putting it back together would be a great inconvenience to say the least. The largest route I work with is UMR by Neil Smith. I may try converting this to HD and see what happens.
I just did a quick experiment with two of my own routes. I converted a route that is 92.0MB and it ended up being 1059.2MB. Then I converted a different route about the same file size at 94.4MB and it ended up being 948.5MB. The first route is rather mountainous while the second one is mostly flat.
Here are 4 routes I have converted and the size comparisons between normal and HD. Route sizes are in MB.

Route Normal HD Ratio
A 95.1 687.2 7.23
B 22.8 209.2 9.18
C 18.6 273.0 14.68
D 59.4 372.9 6.28
SW1500 #1 92.0 1059.2 11.51
SW1500 #2 94.4 948.5 10.05

The UMR route I mentioned is 584.1 in normal mode. I am afraid to see what the HD size is.

It's interesting to see the great difference in the ratios of the HD routes versus the normal route. I need to dig in and see if I can identify why this is.
Here is a big part of the reason.

A baseboard made up of 10 meter grid squares equals 1 polygon per grid square. 72 x 72 = 5184 polygons.

A baseboard using 5 meter resolution has four 5 meter polygons per grid square so 5184 x 4 = 20736 polygons.

HD Terrain is procedural terrain so its resolution is dynamically adjusted based upon the distance from the player's Point of View (POV) so we're comparing apples to oranges with polygons so instead lets consider data points that must be saved for the 0.125m resolution of HD Terrain. Since you can paint a texture at that resolution then the file format for the route must store the exact location you painted the texture. So 0.125 divided into 10 yields 80 locations that a texture can be painted within each 10 meter grid square versus the 1 location of the 10m grid or 5m grid since their smallest brush size is 10m. This might be the reason for the 16 texture limit as this allows a compression algorithm similar to the one that jpeg files use when the conversion is done. Picking the 16 most used textures and filling in the gaps from neighboring textures. Interesting, I've noticed that the smallest a texture can be scaled is the same 10m scale meaning that painting at a higher resolution means you are just revealing a portion of the texture's larger size. This really opens the door for mixing just a handful of textures in a multitude of ways. Very clever stuff.

A good test would be to compare a blank baseboard to the same baseboard converted to HD. I would think the ratio would be more consistent.