Textures & Texture Maps in SketchUp: Difference between revisions

Once you get into modelling for [[FlightGear]], you want to use textures. They give the certain touch of reality to every model. This tutorial shows you how to embed your own textures into a [[SketchUp]] (SU) model on Mac and Windows.

=== Copyright issues ===

Any textures found in the SU paint-box are subject to Google copyright. As Flightgear operates under the terms of the [[GNU General Public License]], model makers must not use any item, be it texture, photograph, or code etc., unless it has been released under the terms of GPL.  

You can see all the details for GPL at: http://www.gnu.org/copyleft/gpl.html  

The only things you can safely use in the SU paint-box are the named colours. I recommend you open the ‘Colours’ or the ‘Colours-Named’ menu, and do everything from there, ignoring the rest of the main paint-box menus. That way you cannot accidentally use something you shouldn’t.

=== Making your own textures ===

You can apply either a color or an overlay image (texture) to your model. Colors are easy, simply pick one of the predefined SketchUp colors. But it gets really nice and realistic once you use images. Let's assume you want to overlay ribbed concrete:  

# Upload that photo to your computer, then, in your photo processor (iPhoto on Mac; [[GIMP]], [http://www.irfanview.com/ IrfanView] or any other on windows), ‘Crop’ it to show just the square metre, and export it with a good ‘highest detail’/’lowest file size’ compromise (‘export to web’ in iPhoto).

# During that export procedure, select a pixels size which is compatible with FlightGear - that means its resolution must exist of squares of two (eg. 2⁰=1, 2¹=2, 2²=4, 2³=8, 2⁴=16 and so on). That gives you possible resolutions like 2x2, 2x4, 8x32, 256x16 and all the like. If you don't do this, FlightGear can show the image, but only after a resizing procedure, which eats up processor capacity. So you want to do that for FlightGear before applying the image to your model. You can rescale distorted images in SketchUp later again.<br />If this is to be the only texture for this model, try to keep the pixels as small as you can without losing too much detail. If it is to be part of a texture map (see below), you can keep the high pixel count at this stage to preserve detail, though it still needs to be set to the 2, 4, 8 etc.sizes.<br />[[File:EXPORT.png|x356px]]<br />If your photo processor does not allow you to set the pixels, use another like Preview (Mac) or Gimp to pixel size the exported photo.  

[[File:Textures_transparent.png|thumb|Semi-transparent textures]] Semi-transparent textures are a powerful tool. Especially when you want to model mesh, banisters, scaffolding etc., you can use semi-transparent textures to minimize the complexity of the model. Like in the model to the right.

It's the [http://scenemodels.flightgear.org/modeledit.php?id=220 gasometer] by Jon Stockill. To simulate the framework, he uses a minimal image that is transparent except for the metal parts:

Another good example is the roof structure of the [http://scenemodels.flightgear.org/modeledit.php?id=795 A380 hangar] in Frankfurt (EDDF) by Christian Schmitt.

=== Loading your texture into SketchUp ===

* '''Mac:''' Select ‘New Texture’ from the ‘Colour’ menu inside the ‘Colours- Named’ section of the SU paint-box.<br />

Select your photo, and click ‘Open’. This will take it into the paint-box with whatever name you saved it with.

In the SU paint-box you can give your new texture a unique name. Try to make this name relevant to the model you are making. This could be useful in reuniting them if ever the model and its texture get separated. For use in FlightGear there should not be any gaps in the texture name.  

You need to set the size of your new concrete texture to 1x1 m. This means: If the area you are using the texture in is bigger than 1 metre square, the texture will be repeated every metre in every direction, until the whole target area is textured.

'''TIP:''' ''When making a texture of an item like a door, or window, it is a good idea to include it’s measurements in the individual texture name. The name of each item in the paint- box appears when you hold your mouse pointer over it. This helps when marking up your model with its target areas.''

'''TIP:''' ''When you first start modelling, there is a lot of satisfaction to be had from making very detailed models. The downside of that is the large file size produced. This affects loading times in FlightGear.''

''By all means make your detailed model - take a snap for your own collection - then try to minimise the face count (MaverickAlex has produced a tutorial on this, see: [[Howto: Decrease the number of faces]]''

''Alternatively, you could keep your detailed model, and make a copy of the file to reduce the file size on. This copy would be the one you send to the [[FlightGear Scenery Database|scenery database]].''

'''TIP:''' ''You could save a lot of file space by snapping the whole side of your model and making a texture of it to keep in all your hard earned detail, but with only one face on the texture to be counted.''

=== Correct display of texture colors in the AC file ===

Later, when your model is done and you [[SketchUp to AC3D exporter|export it to AC format]], the textures will be defined in that AC file. There, the RGB settings should be <tt>rgb 1 1 1</tt> for a correct display of the texture colors ([[AC files: Basic changes to textures and colors]]). To insure that this will be done automatically, you should set the color of the texture to <tt>rgb 1 1 1</tt> already in SketchUp. The texture will appear whiteish in SketchUp, but correctly after export. You do that during the definition of the texture. In SketchUp, <tt>rgb 255 255 255</tt> is the same as <tt>rgb 1 1 1</tt> in the AC file:

=== Making a texture map ===

This can all be accomplished in Sketchup - though some modellers prefer to do it in a separate application.  

'''TIP:''' ''I do it all in SU to ensure the measurements are correct and match my SketchUp model.''

First you need to make each of the textures you are going to use in your model. You can produce textures (as described above) from photos, or from drawings you may have done in SU, or another application (eg. iWorks or Appleworks for Mac). You can use quite high resolution pics or drawings for these, thus keeping more detail, as you will be minimising the pixels on the final map stage.

Now use the SU 'Square' tool to cover your square of targets as tightly to the edges as possible. Make this a perfect square, even if you have to include some of the background between the targets.  

Use the SU measuring tool to measure your square. Note the measurements down for future use.  

Use the inside corner of each of those corner squares as the limits of your screen-shot (Photo). In this example the photo will be equal to 4.7m x 4.7m when you take it back into the SU paint-box as a new texture. Use a photo processing application (like Gimp, Photoshop, (for Macs Preview or iPhoto will do as well)) to make the pixels a square of two. Keep the squared pixel size to the smallest one that keeps the necessary detail in the textures. Bear in mind most models are viewed as a 'flypast', which means at a distance. Try a couple of sizes to decide which will do the job effectively.

Go back to the SU paint-box and make a new texture from your photo. Make sure this new texture has a unique name, and the width and height of this texture is equal to the square you covered the targets with (hopefully you noted the measurement earlier).  

# In the SU paint-box, select your new texture.  

# Another right-click at this stage will give you the option to rotate the texture if necessary. Do not forget to click 'Done' (right-click menu, or ctrl+click menu for Macs) when you have got the correct part of the texture map in your target area.  

Remember to erase the duplicate square of targets in your SU file before you export to .ac.  

 

 

That is it.  

I hope this tutorial is helpful to you.

(Special thanks to Alex Park, who showed me how to make texture maps.)

(And David (D-79) for the PC details to match my Mac instructions)