Editing Vehicle Creation (section)

===Will It Blend?===

To import the model into Blender, go to File->Import, and choose Collada 1.4(dae).  The import dialogue will appear in one of the windows - if it's too small to see, ctrl-up will maximise the window.  Choose the file you want to import, press the "New Scenes" button, then press "Import and Close".  You should see your model appear after a short pause.  If you don't it may be too big to see - press a, then s, then move the mouse until it appears and press the left button.  You may need to change which scene you are looking at too.  Next, clear the parenting information (Alt-P, then choose "clear track").  This avoids some problems with rescaling parts of the object.

[[file:Blender_Screen1.jpg]]

You can see the current poly count in the top bar.  Right now it's 9492 in my version, and we need to get it below 1500.  You're mostly on your own here, but there are a few tricks I've found along the way.

=====More Deletions=====

You should find the model is grouped into objects.  There are usually more objects here than in Sketchup for some reason.  Delete everything you don't need.  As with sketchup, hiding things temporarily helps you get at the inside.  You could also try hiding everything you want, then deleting what's left.  Make sure to remove all of the interior - we don't need it, so it's all wasted space.

=====Double Skins=====

The export from Sketchup makes everything double sided, which means we have twice as many faces as we need.  Sometimes you can select these by material, and sometimes you just have to use the remove doubles tool, then clear up the mess afterwards - make sure you're in texture mode so you can see which faces are flipped the wrong way.  Auto recalculating normals (ctrl-N) works pretty well for simple objects.

[[file:Blender_Screen2.jpg]]
''Removing doubles leaves half the faces flipped the wrong way''

[[file:Blender_Screen3.jpg]]
''Recalculating normals fixes it nicely''

=====Window Cleaning=====

Remove anything that would look just as good painted on - especially logos.  Windows etc. are better as part of the texture, because it makes it easier for artists to modify later.  Here I'm stripping out the door handles by merging the vertices (w->merge->at centre).

[[file:Blender_Screen4.jpg]]

=====Auto Reduction=====

There are two ways to automatically reduce the poly count.  One is easy to use but gives pretty bad results - Mesh->Poly Reducer from the scripts window.  I used this on some of the earlier models, but I try to keep it as a last resort now, because the results tend to be ugly.
The nicer way is the decimate modifier.  Because it's a modifier you don't lose data, so you can add modifiers to each object separately until you get the poly count you want, then apply them all.  The only problem with decimate is that it only works on manifold objects - that is, simple closed surfaces with no holes in.  You can use ctrl-alt-shift-M to select non-manifold vertices, which helps a bit, but it's still a pain.  The results are good though.  You'll probably have to join all your objects together to do this, so save first.

[[file:Blender_Screen5.jpg]]
''Manual cleanup gets us to 3500 faces.  I got bored removing the windows, but decimate should do a pretty good job''

[[file:Blender_Screen6.jpg]]
''Decimate modifier does the rest''

If you have a more complex model, you could try decimating the individual pieces, which should let you adjust where you want more detail.  I just finished a model where 1/3 of all the faces were in the wing mirrors, which is not ideal.

=====Tidying Up=====

Once you're close to 1500 polys, you also need to make sure your model is clean.  By this I mean there should be no holes, no stray edges or faces, and no weird geometry (infinitely thin edges, etc.).  If you used a decimate modifier you're probably nearly there anyway.  It's up to you how far you go with this, but it'll make the texturing easier.  Once you've finished, save to a new file (because the next bit is irreversable) and apply all your decimate modifiers.  Then select all objects and join them together.  You should have a single object consisting of a single closed surface.  With that done, it's time to start skinning.