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Developers:
Steal These Ideas

One of the reasons that Spittler Engineering was founded was out of frustration that many good technical ideas for improving the quality of locomotive and car skins were not being used by members of the re-skinning community.  It has therefore become one of the core missions of the organization to actively promote various ideas, techniques and even parts of textures that we believe would result in better skins for everybody.  We greatly appreciate it when others give us credit for work of ours that they have borrowed, but we have done a good job of reigning in our legal staff and don't wish to require that this be done.

Texture Techniques:

Don't Over Saturate Colors.  Many people getting started in re-skinning cars and locomotives often use colors which are much too saturated.  Saturation refers to the balance of grey vs. "pure color" in an actual color.  Quite a bit of realism can often be gained by adding more grey to the color balance of a given color.

Use Layers to Create Textures.  We strongly recommend becoming proficient with using "layers" within your graphics software of choice (we use Paint Shop Pro 7.0).  This has a number of advantages.  The most significant is that layers can be deleted, added or changed at any time.  Without using layers, it is often difficult or impossible to go back and redo early additions.  (FYI, we used almost 100 texture layers for each of the two images required to re-skin the GP38-2, and we wished that we would have been able to use more!)   For those using Paint Shop Pro to do their designs, we recommend using the .psp file format for your "master".  This will allow you to use all the special layering features designed into PSP.  You can then "save copy as..." to generate the .tga and .bmp files required by the "makeace" utility.

Create and Use Temporary "Reference" Layers.  Create "temporary" layers which you can use to "rough out" the sizes and locations of various features.  Use these layers to mark the boundaries, centerlines or anything else that requires some trial and error in positioning (going back and forth between MSTS and your graphics program).  It is best to use bright, high-contrast colors on these layers.  You can turn these layers off when you don't need them, and of course you don't want them on for the final output.

Add Shadows and Highlight.  Consider adding shadowing and highlighting to your textures.  A horizontal panel seam, for example might be represented by a thin horizontal dark line (most people get this part right) with a horizontal lighter colored line just beneath it (this is the part many people miss).  We add these highlights and shadows on their own layers, rather than directly to the base textures.  That way you can adjust the "strength" of the shadows and highlights separately using the "slider bars" in the layer control panel.  We have found that horizontal seams seem to benefit from stronger highlighting than vertical seams.  Also, be aware that the use of highlighting for seams may require a fairly subtle touch to achieve a natural look.  Be careful not to overdo it.

Few Things are Black or White.  If you are rendering a surface that is "black", try using dark or even medium-dark gray instead.  Real solid black doesn't occur in nature as often as you might think.  The same is true with solid "white" areas.  Experiment with light gray instead.

Add Weathering.  Weathering can add a lot of realism, but can involve some experimentation.  Be sure to use separate layers for weathering techniques!  We had some luck by creating a layer of very large wood grain (we're talking three feet or so between "grains") over our base textures, and specifying this layer as "hard light" within the Paint Shop Pro layer control panel, and then adjusting the opacity to suit our tastes.  The wood pattern we used was obtained by setting the "Style" window to use a "pattern", instead of a solid color, and using the "Phone Pole" pattern to create the wood grain pattern.  (The style window is where the current color is typically displayed.)  For dark surfaces, we specified the wood grain texture layer as being a "luminance" layer blend mode.  The key, is experimentation.

Fix Blotchy Colors.  Texture files that are ultimately converted to "ace" files containing an alpha channel are unable to display nearly as many colors as those generated without.  This creates undesired blotchy variations in color.  An easy technique for reducing this problem is to add "noise" to these textures.  This has the effect of "dithering" the colors, in a similar manner to how ink jet printers represent a continuous range of colors.  In Paint Shop Pro, we specify "uniform noise" from within the "effects" menu.  We usually make a backup copy of a layer before adding noise to it.  This way if you need to go back and change the layer in the future, you don't have to worry about matching the noise you added.  Just make the change to the "pre-noise" backup copy and re-add the noise.  Often it is best to only add as much noise as necessary to solve the blotchiness problem.

Add Non-Uniformity and Imperfections.  Reality is not usually as perfect and uniform as hand rendered textures are.  If you compare photographs with re-skinned models, you will probably notice, for example, that panel lines on the photo are inconsistent or even invisible in places.  Try to learn as much as possible by studying actual photographs.

Sharpen The Textures.  Paint Shop Pro 7.0 and most other advanced graphics software have a function for sharpening the image.  We found that this added a lot to our textures, just as it did to our screenshots.  We never sharpened our original PSP images themselves.  We only sharpened the "tga" and "bmp" files after we created them using "save copy as".  The reason is that if, after sharpening a layer, we decided to go back and change something, it would be hard to match the amount of sharpening in the unmodified portion of the image.

Window Treatment:

Darkened Interior.  The interiors of the locomotives should be dark.  Look at photographs of locomotives.  Although the interior surfaces of real locomotives may be painted light gray, for example, the interior looks very dark when viewed from outside.  This also helps realism at night time.

Window Tinting.  Some locomotives have darkly tinted windows, others have un-tinted windows.  Make a conscious decision how the windows should look.  Even if "un-tinted" windows are preferred, the textures should not be made completely transparent.  Some opacity is necessary in order to successfully model reflections and dirt.

Reflections.  We modeled reflections using a black background with wide white streaks on top of it.  Getting this right required a lot of playing around.  Be sure to study the GP38-2's "tga" file if you are interested in how we got our window effects.  (Don't forget to examine the alpha channel, since this is a critical part of the operation.)

Window Dirt.  We were very satisfied with our attempts at achieving a realistic representation of window dirt.  In order to do this, we used our best guess at the color of dirt, and then added a great deal of uniform noise to the result.  The high amount of noise was necessary to account for the fact that the layer is very transparent in this area.  Compare the "BNSF 2098" "tga" file with the locomotive as it is represented in Train Simulator in order to get an idea of how we got the look we got.

Wiper Marks.  The wiper marks over the window dirt add a great deal to the realism of the window appearance.

"Engine" (.eng) File Lighting Techniques:

RTFM (Read the Fine Manual).  MSTS installation disk 1 includes a number of useful technical documents in a self-extracting zip format.  (Look in the "techdocs" subdirectory.)  If you haven't yet done so, extract these files and store them somewhere handy.  Among the many valuable documents included is a document describing lighting techniques.  You will probably want to read this if you plan on modifying the lighting in the "eng" file.

Incandescent Light Colors.  The default headlight color, and those of most add-on locomotives we have seen, is specified as being pure white.  This isn't really a natural incandescent light color.  We recommend tinting this light a yellowish-orange color.  The difference can be dramatic.  Experiment with this.  Since the apparent color of the light is influenced by the color of the texture behind it, you may find that the optimal "incandescent" light color for different light applications is different.

Reflective Glint on Wheels, Railings, Un-Powered Lights, etc.  We added "glow" lights to simulate reflective glint on shiny parts of the locomotive such as the wheels, hand railings and the lights (when they are in the "off" configuration).  Be aware that there seems to be limitations on the total number of lights within MSTS activities.  Our original BNSF 2098 ".eng" files had 47 lighting objects. This worked well in many situations, but caused a problem with some more complicated activities.  We later reduced the number of lighting objects to 20. This sounds like a lot, but we had to remove some of our reflective glint due to this limitation.  By the way, since the glint represents reflected sunlight, pure white seems like a perfectly natural color for this application.

Flashing Ditch Lights.  The ditch lights for the default GP38-2 flashed far too quickly, and transitioned between on and off instantly, very unlike the characteristics of actual incandescent lights.  We have slowed down the blinking and added a more realistic transition between on and off.  You might want to study the flashing ditch light section of our BNSF 2098 eng file as a starting point.

Azimuth and Elevation Min and Max Values.  The azimuth and elevation parameters for glow lights allow you to specify the how "omni-directional" these lights are.  What happens is that the disk of light will always remain perpendicular to you as long as your angle from the glow light is between the min and max values.  Beyond that angle, the disk stops "following you", and will get dimmer as you move farther away in angle.  The MSTS documentation incorrectly lists the order in which these parameters need to be specified.  The correct order seems to be Azimuth( center min max ) and Elevation( center min max ).

General Philosophies and Mind Games:

Why Doesn't My Locomotive Look Like a Photograph?  We ask ourselves that very question every single time we load up a new version of a skin we are working on.  It is kind of a mind game.  We look at the locomotive and try to pick out very specific things that look different than they would in a photograph of that same locomotive.  In many cases we then look at images (available from a number of sources online) to try to better understand the issue.  This is how we came to decide that we liked darkened cab interiors best.  When we looked at photographs taken from the outside, the cab interior almost always looked dark, even though the windows weren't tinted.  Perhaps ironically, it often seems easier to successfully use this "mind game trick" on a skin which is relatively good, rather than one which isn't.  The key, though, is to concentrate on one thing at a time.  (Highlights and shadows are often the issue.)

Go for Balance.  One of the advantages of using a lot of layers for things like panel lines is that you can later go back and adjust the opacity of each layer to get a good balanced look.  We used different layers for horizontal and vertical panel lines, because we found that the best opacity of the vertical and horizontal lines were different and needed to be adjusted separately.

Finishing Details:

Make the "loco.ace" File.  The "loco.ace" file in each locomotive subdirectory contains the image which is displayed when selecting locomotive "details" from within MSTS.  This file appears as if it can be created in different sizes depending on the desired resolution of the displayed image.  We decided that since this image is relatively unimportant, we didn't want to use up too much space, so we used a 256x256 image to generate it.  MSTS seems to squash the square 256x256 image you use to generate the "ace" file, so you actually have to stretch the image out vertically prior to generating the "ace" file.  (This may work differently for different resolution ace files.)  If this sounded confusing, don't worry.  Just try making a loco.ace file from a 256x256 file, and you will probably be able to figure out what you need to do to make it come out right.

Stuff to Take Directly From Our Textures:

Use Our Alpha Channel and Window Textures.  For those doing their own GP38-2 textures, we invite you to use "BNSF 2098" as a baseline.  The biggest advantage to doing this is that the window sizes and treatment can be retained..

Use Our Wheels and Trucks.  The wheels and trucks of "BNSF 2098" can be easily taken and used on other GP38-2 re-skins.  Please feel free to do so.

 


  2001-2002
 Judd Spittler
 


Questions?  Comments?  We are always interested in hearing from you.
judd2@juddspittler.com