Building in GMAX - FSX extras

FSX introduced some new thing we can use to make our models look more realistic. I'll cover a couple of them here, as they are simple to add and should be part of any basic scenery for FSX.

First up is Self-shading, or Volume Shadow. This allows an object to cast shadows on itself, or on other objects. In previous versions, an object shadow was projected onto the ground only, so this new feature makes things look more realistic. This is simply an option available when you create your Material in GMAX. You just scroll all the way down to the bottom of the Material Editor, to the Advanced Parameters, and turn on 'Volume Shadow'.

However there are some requirements for self-shading. A model must be 'manifold' for the shadow to work properly. This means, basically, that it must be fully enclosed, without holes or missing faces. For instance, in the part to optimise our building here for FS2004, we would delete the bottom face. It'll never appear in the sim, so it may as well not exist. In FSX, however, for self-shading to work, we need to retain the bottom face, otherwise it will no longer be manifold.

For our simple model we've created, self-shading doesn't really do much, in that there is no part of the model which protrudes out to project a shadow on the model. However we may want to place our building close to something else, and have the shadow appear on the nearby object.

If you look closely at our real building here, you'll see that it does cast some interesting shadows on itself -- in particular, there are strips of timber on the blue wall, a white board stuck to the wall, and an inset concrete foundation which picks up a shadow. You may, if you wish, model all this geometry for the best result in FSX. In FS2004, you may be better off just suggesting these features in the texture, rather than modelling them. Note that I didn't model these features in the payware version of this building.

Next we have Specular shine. This was available in prevous FS versions, but is enhanced in FSX. Now any object can have a degree of shininess. Note that this is different from reflectivity, which we'll cover soon.

An object can now include a Specular Map, which is an additional texture designed specifically to add different degrees of specular shine. This texture normally includes a specular colour map, plus a specular strength map. The colour map can be just a duplicate of our normal texture, and the strength is included as an alpha channel, or Mask.

This simple guide won't include any details on how to create or apply a specular map, but we'll look at something a bit simpler. One issue with specular maps is that they add a lot to the texture overhead -- a specular map for our building here, for example, needs to include a variable alpha channel, which would require a DXT3 or DXT5 format. This makes the texture a lot bigger, and in some cases can triple the texture requirements for an object. This means that it needs to be used sparingly and thoughtfully.

Each object, if it doesn't include a specular map, can still have a specular shine. This is controlled by Specular Color. The Specular color can control the actual colour of the specular shine, but more importantly it can control the strength. The lighter the specular color, the more shine. To remove any shine, make the specular color black. This will apply to the entire object (or the bits of it with this particular material) so this takes some thought. A mainly white object, such as a white-painted building, can benefit from a degree of specular shine, but on a darker building, specular shine can show as a washed-out texture -- everything takes on a shine, even the dark bits. So darker objects can benefit from less specular shine.

Reflection -- in reality, we see a lot of reflections at our airports, mainly from glass windows and doors. This is a simple feature to use, and adds a huge amount of realism. Unlike Specular Maps, the overhead is smaller, and the visual result is greater.

To create a reflective map, we need to add a mask, or alpha channel, to our normal texture. You will really need to do some study within your normal graphics software if you are unsure how to do this, but it'll give you some new skills which will be very useful for scenery design.

Our alpha channel in this case needs to show white where we don't want any reflection, black where we want strong reflection, and degrees of grey for different degrees of reflection.

Here's our normal texture again:

...and here's our simple alpha channel: (I've given the alpha texture image a border here for clarity, the actual texture or alpha channel doesn't include a border.)

Whereas we were probably using our original texture sheet as a BMP image, we can no longer do so here because a BMP image cannot include an alpha channel. Designers who use PhotoShop normally save in the normal PhotoShop format (psd) but if you don't use PhotoShop (I don't) then a handy format is .TGA. This allows an alpha channel, and can be opened in ImageTool.

Note that the iron roof reflects light, but here specular shine would be more appropriate. Reflectivity is really for materials which reflect an actual image, such as glass.

Now when we drop our texture into ImageTool, we create mipmaps as usual, but now convert to DXT3 format, which can include a grey scale alpha channel. Now Save As in DDS format as before.

To apply the reflections in GMAX, we go to the Special Functionality section in the Material Editor, and turn on these:
Blend environment by inverse of diffuse alpha; and
Use global environment map as reflection.

The reflection we will see in our windows is not an actual reflection of what is in front of the window; it is the default Environment Map. You can create your own Environment Maps, if you wished to have the reflection more accurate, but that is well beyond the scope of this tutorial.

Another 'basic' texture property is Bump mapping, but this is not really suitable for our building here -- it is more suited to natural materials, such as stone.

So here is what we end up with in FSX. Note that I've added some bits, which I'd recommend you try. I said at the beginning that our building wouldn't have the overhanging bits, for simplicity's sake, but you may wish to add them. How? Think in terms of extruding faces, shifting and welding vertices -- all techniques we've covered here.

Note the specular shine on the sunny side, and the environment reflection in the front glass. Not entirely obvious in a still image, but very realistic as you taxi past! This does not show Volume Shadows, though.

Our tutorial is now finished. Be aware that this is just a small part of designing quality flightsim scenery, but a very important - and interesting -- part. There are other tutorials available on the site covering more general airport design, plus some on creating quality textures. Good luck with your scenery design!

These tutorials are designed to show that although scenery design isn't the easiest thing in the world, it is simple enough to get into if you take little steps, and experiment a lot. It took me a long time before I had enough skills to design for a living. If you wish to say thanks for these tutorials, the best way is to buy my scenery:)

I recommend the gmax Bible as the best GMAX resource available. Click on the link to purchase from Amazon.

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