Using SCABs for the Darjeeling Himalayan Model Railway Project

By John D'Angelo and Peter Pardoe-Matthews

Ok folks, calm down, we’re not using union busters to work on the Darjeeling Himalayan Model Railway project. We’re using a unique new system to allow different people to contribute to the making of a highly detailed Trainz-based full-scale model of The Darjeeling Model Railway.

At this point in our project, Bill Slack has been able to accurately run the main line from Siliguri India to the railway’s last stop at Darjeeling in the Himalayan foothills. This was a major feat of work by Bill and frankly, I am amazed at how well he did this. We will be focusing on the Ghum Station area as we describe the process of creating and using a SCAB (scene content assembly board).

The accompanying Trainzmap image has had all the labels removed for clarity. Siliguri is in the bottom right corner of the map and Darjeeling is at the top. Ghum is located about nine miles south of Darjeeling.




In the above view the labeling has been left in, and each square is one Trainz baseboard in size.


A single baseboard.

The model of the route Bill Slack created is over 50 megabytes in size and the large size created problems when it came time to share the file for detailing. It just is not easy to send and receive a 52 megabyte file amongst a group of different people. Something had to be done to create a system where folks could work on sections of the route, then contribute that work to the main body.

Bill Slack and Peter Pardoe-Matthews worked on creating a system that could accomplish this, and the SCAB system was born. Peter has written a description of the process for us, and here in Peter’s own words is his description of the SCAB system.

Peter:

The DHR Narrow Gaugers Group SCAB system. The route that the group is creating has many areas of crowded scenery that have to be as prototypically accurate as possible. Placing of scenic items has to be made in relation to previously laid track as the track and buildings are very closely related. A point to be mentioned is that the route, which is digital elevation model (DEM) contoured, has heights that vary from 300 feet to 7000 feet. Truly mountainous country!

Since various group members will be sharing the work of adding scenery and textures, it seemed at first that the need to transport the route from one member to another would be difficult both from the size of the route and the time involved as each member in turn took possession.

It was originally thought that as Surveyor will allow a Copy/Paste operation, members could work on individual boards that would be attached temporarily to the main route and copied to the destination board. To do this the track layout had to be accurately transferred to the individual work boards, and initially this was attempted by using a screen shot of each area. This failed for two reasons: the board edges were not visible and the grid squares were distorted by the previous contouring, making accurate positioning impossible.

This was when the SCAB system was developed. SCAB = “Scene Content Assembly Board”. If you don’t like the acronym, think of ‘Work Board’.

The process is as follows:

Trainzmap is used to produce a large scale single board bitmap showing only the track and spline points. This bitmap is selected to be slightly larger than one board at the largest possible enlargement. It is important that the Trainzmap export function is NOT used. The Windows Print Screen function gives a better image.


Image from Trainzmap. Note the track spline points.


Enlargement of station area from Trainzmap.

This image is then trimmed to precisely one board size, and resized to a 1024 x 1024 pixel image. Identifying labels are added and the main black-on-white image is saved as a .tga file. The image is then converted to white-on-black and saved as a mask bitmap. (A word of explanation: there is no need to reduce the texture size or make any effort at poly reduction as this texture, and the object it is applied to, are both removed before any serious running takes place.)




Mask and main image from Paint Shop Pro.

We then create a 720 x720 metre plane in gmax. This is textured using the previous image, ensuring the image is accurately placed on the plane. This is then exported as a Trainz scenery object.


Image in gmax with opacity increased for better definition in screen shot.

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Article and screen shots �2006 John D’Angelo and Peter Pardoe-Matthews. All rights reserved.