3D to 2D art tutorial

This is a quick tutorial on how to make 2d art assets, such as icons, from 3d objects. For this tutorial, I will be using Sketchup and GIMP. Both of these programs are free and available on multiple operating systems, so anyone is able to get started.

1) Build the 3d model (this is beyond the scope of this tutorial because it is a very extensive subject. I do have information about it in older posts, and will most certainly continue to do so in future posts as well. Your finished model might look something like this:

2) Make certain that  View > Shadows is checked and fill the background with a bright color that will not be in your model. I use green (just like a green screen for movies). You can do this by going to Window > Styles and then making a new style. Go to the Background tab and check the Sky and Ground box, then set the colors for them.

And it show now look like this:

3) You need to export it to an image file so that GIMP can understand it. Sketchup also runs a very very basic rendering operation. It's basically applying anti-aliasing and smoothing to the image.

File > Export > 2d Graphic

Make certain to save it as a .png file.

4) Now, load it into GIMP and select the Select By Color tool from the toolbox. Select the green (you may have to select multiple sections to get all of it by holding the shift key) and delete the color completely. This will result in some left over residue:

Simply repeat step 4 on all the green pixels until they are gone.

5) Now use the fuzzy select tool to select all of the dead space, similar to how you selected the green in step 4.

When you have all the dead space selected, go to Select > Invert Selection. This will select your entire object without singling out dead space, color, etc.

6) Icons should always be a factor of 2 and square. That means you can always divide the pixel dimensions by 2 and the height and width are the same value. This means we need a canvas that fits these requirements.

Select Image > Canvas Size... from the top menu and change the dimensions to the nearest even number (you'll want to use the higher number if you have a rectangle). Note: Make certain the chain on the right side is broken! Otherwise, you will be forced to scale in the same ratio.

Make certain you press the Center button! Then press Resize.

7) Now we have the proper dimensions. In the layers window, right click and select Add New Layer twice. Name the first one Shading and the second one Lines. You should now have layers that look like this:

8) Select the bottom layer (it should have your image name or Background) and select all the dead space. Invert the selection just like step 5 (Select > Invert Selection). You should now have only the image selected.

Select the Shading layer by clicking on it and then click the Bucket Fill tool and select your desired color. I'm going to use one similar to the MWO theme.

Set the Opacity to 50% and then click in the selected area in the main screen:

9) Now, this is good, but you'll notice the details are muffled, specifically the lines. So now we click on the Color Select tool again and make certain the bottom most layer is selected. Click on a black line anywhere in the image to select all black lines in the image.

10) Modify the Bucket Fill options so that Opacity is 100% and the color is Black.

Then select the Lines layer by clicking on it. Now that it is in focus, hold the Shift Key and click inside your selection. Your image should now have much crisper detail:

11) Last step! Simply select Image > Scale Image and set it to the desired icon size. I'm currently using 100 x 100 px:

And now you have an icon that's ready to use!

Some tips for consideration:

• Keep your final icon size in mind when designing your 3d model. It's possible to spend days making a professional model, but you'll lose 95% of that detail when you shrink it to an icon!
• Create your theme and color scheme before making finished icons. Otherwise, you'll end up fixing them all again, and again... and maybe even again.
• Save the .xcf file! Always, no exceptions! You can't edit layers once the image has been exported and flattened.

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Here are a few more icons I've made:

Mechwarrior Online

Mechwarrior Online just hit open beta! It's completely free to play and has plenty of big-robot-smashing fun. Check it out at http://mwomercs.com/. For those of you curious about what it's like, imagine Mechwarrior 4 thrown into a blender with World of Tanks and League of Legends. This tutorial by the great guys at No Guts No Galaxy will help get you started:

The Importance of being Hollow

Let me start this with a bit of random trivia. A viagra knock-off company in India has generated 9 hits on my blog this week. Maybe they enjoy 3d modeling?

Anywho, as the title says, it's very important to be hollow. At least if you're a 3d model. See, all 3d printing companies charge per cubic centimeter of material that your model contains. This means that models can start to cost a lot of money. How much? Frosted Detail (FD) runs $2.39 US per cubic centimeter. If you wanted a high quality 16mm die, that would be 1.6cm^3 * $2.39 or $15.66 per die! Yikes!

To decrease this cost, we hollow out our objects so that they use less material. Generally this does not effect the component, since it's either too small to be effected, or meant for a prototype and will never be used.

*SAGE ADVICE* If you are planning on creating masters for mold making, you will want to be -VERY- wary of hollowing your models. Many mold making processes involve a lot of pressure and heat, and will result in a broken master and ruin mold if the model is too weak. Generally speaking, I advise anyone who plans on 3d printing masters to either use wax for bronze casting or make certain that your prints will be very solid, even if they do cost much more.

Alright, so lets look at the quick and dirty method of hollowing out an object. First open up the object you want to hollow out. In my case, it is a very fancy looking box magazine.

An important thing to keep in mind is structural integrity, both as a requirement for printing and for functionality. In the case of my magazine, it is going to be printed in Frosted Ultra Detail (FUD), which has a minimum wall thickness of .5mm (half a millimeter). In addition, it is meant as an accessory to a machine gun, so it must be able to lock into the machine gun's magazine well without breaking. This means I have to be careful about the guides I design to fit it in place:



First I'm going to copy the magazine by selecting the Move tool (or M) and pushing the ctrl key once:



Because I don't want to weaken the magazine guides, I'm going to remove them from the copy:



Now that it's cleaned up, I can scale it down, say, 15% using the Scale tool. To scale it exactly 15%, use the scale tool as normal, but type .85 in for the scale amount. If your remember math class from all those years ago, it means you are reducing a number TO 15% of it's original (or reducing it by 15%):



Now for the tricky part. we need to move the smaller magazine so that it is in the exact center of the original. We can do this by creating some center guides. But keep in mind that the smaller version won't light up exactly with the larger one, but we can still find a good fit by using the guides:



Now, hide part of the large magazine by selecting half of it, right clicking, and selecting Hide from the option menu. This will allow us to move the smaller magazine into place:



Remember your minimum material thickness, and measure to be certain. If you believe some areas may be too thin, just scale down the model by 5%. Once everything looks good, select the entire model, right click on it, and select Reverse Faces from the menu. This will make the distinction between the inner and outer walls:



Almost there!

Now Select both models by drag selecting. Right click them and select Explode from the option menu. This will break both of them out of the component state, and allow them to be recombined as a single model:



And that is the cheap and easy way to hollow out a model. You can actually hollow very complex models in a similar way. However, not all models can be hollowed using this method, but I'll cover that in another blog post.

Until then, thanks for reading!