CAD figures for publication

[FayRhodes]

If you are preparing LEGO figures for publication, you know how confusing the CAD software—MLCAD, PO V-Ray, LDGlite, LPub…—can be. If you’d like the benefit of my experience, the following is my method for getting large dpi pictures for print publication. (If anyone has a better way, please let us know about it!)

Just in case you don’t know, your screen renders graphics at 72 dpi. Publishers want a minimum of 300 dpi for print publication.

First of all, use LPub 2.2.0.2. (It says 2.2.0.1 when you choose “About…”, but the download says it’s 2.2.0.2.) I know this is a very old version, but unfortunately, the newer LPub version 2.4.20.0 renders all the steps as PNGs. (You can only get a whole figure in bitmap.) It’s possible that the new version 3 Alpha can produce higher dpi figures, but version 3 is a too buggy for my taste right now.

I use POV-Ray 3.6. If you want to use Mega-POV, you’ll need to install it and POV-Ray 3.1 on your computer. (Mega-POV will allow you to outline all the edges of your images.) I actually prefer LDGlite renderings, but they are not high definition, and, therefore, will not work for publication. I use LDGlite for my working images, and then run POV-Ray for my final versions.

Be sure to open your document first. (I recommend you try this out on a small sub-model first, since POV-Ray and LPub are very slow.)

Select POV-Ray 3.6 (or whatever version you are using) as your renderer.

Under Construction Images, there are two tabs that refer to minimum distance. You want minimum distance enabled. The setting for that and the parts list minimum distance should both be 1000. Choose High Res. --Black and White. I also ask it to crop my figures (on the last tab). I don't know if the latter makes a difference, but I choose it, hoping that will keep my images as large as possible. If your figures start getting cut off (as they do when I use LDGlite), de-select this option. When given the choice, make sure to choose a Camera setting, instead of Orthographic.)

Under L3P, choose high resolution and camera angle. (I set the angle at 30.) Do not choose “orthographic”. POV-Ray will respond with an error message if you do.

Under POV, set the output for Bitmap and increase the dpi settings to
width- 2048
height- 1536

If you’re having trouble with camera angles, make sure you use rotation steps in MLCAD to create the views you want. Remember, you can add multiple rotation steps to get multiple views at any point in the rendering process.

After LPub renders the building steps, you’ll need to convert them to png. (BMP files are HUGE.) I work on a Mac when possible and use Graphic Converter to make this conversion in one easy step. (Does anyone know software in Windows that does this?)

You can check the dpi of your images by scrolling your mouse over the document names. Divide by 300 and you’ll know how big your image will be in print. A publisher may settle for less than 300 dbi, but it becomes less clear and more pixelated as the number drops.

If you are preparing building instructions to post online, I recommend using LDGlite with LPub 2.4.20.0.

[davidjperdue]

Hi Fay,

Thanks for posting this information for everyone! Since I'm also in the process of writing an NXT book (also No Starch), I'm familiar with using LEGO CAD software and have some tips to share.

First, I’m using LPub version 2.3.0.10 (I haven’t switched to the current 2.4.20.0 yet) with Mega-POV 0.7. I've found that outlining the piece edges with Mega-POV is beneficial for the NXT models, especially with the white parts (actually “light stone gray”) in the NXT set. For my book, I’m rendering the building instructions with a dimension of 2304 x 1728 and using the following Mega-POV settings, which can of course be configured in LPub:

Depth difference: 2

Angle difference: 0.35

Color difference: 1

Width: 1.3

Sharpness: 5

Color: black

I’ve had tremendous success with these outlining settings, which I got from the book Virtual LEGO. I have LPub render all my building instructions in png format, which works fine for me; my images, generally speaking, do not get cut off in png format (is this what’s happening to your images?). In newer versions of LPub, you can select Utilities --> Min Camera Distance on the menu bar, and it will tell you what the minimum distance should be. I use this feature as well.

As for dpi, LPub actually doesn't let you control dpi (at least not yet). The width and height controls are only for the dimension of the rendered image, and the dpi remains the same. In my experience, however, using rendered images directly from LPub (which come in at 96 dpi for my computer) with a dimension of 2304 x 1728 work fine for a grayscale book. A color book, however, would definitely be a different case!

Also, about the camera angle, the orthographic setting is desirable, but to avoid errors try using a camera angle of 2. This will be very close to orthographic but should still work.

I hope these tips will be helpful to everyone.

- David J. Perdue

[FayRhodes]

Thanks, David. This is really helpful information. I like having the edges defined with Mega-POV. I didn't even know there was a version 2.3...of LPub. I'm going to try out your settings.

Fay

[davidjperdue]

Yes, try it out and see how it works for you. Although Mega-POV doesn't outline the edges perfectly, it still looks pretty good with these settings. Without the outlining, the white pieces can be hard to see on a white page!

- David

[JimKelly]

David,

Is your book on CAD?  When's it due? 

Jim

[FayRhodes]

White parts blending into the background has always been the biggest problem.

Yes, do tell us about your book!

Fay

[davidjperdue]

You actually posted earlier about my book, The Unofficial LEGO MINDSTORMS NXT Inventor's Guide, which is due in October:

http://thenxtstep.blogspot.com/2007/05/new-nxt-book-coming.html

The only thing that's changed at its Amazon page is I've added a temporary cover. You'll notice that the design of the cover is very similar to the cover on your book The LEGO MINDSTORMS NXT Idea Book, since both are being published by No Starch. The robot shown is Claw-Bot, an aggressive mobile robot that finds and pushes objects out of the NXT test pad.

Thanks!

David

[FayRhodes]

David,

I tried your method using LPub 2.4.20.0, since I can't find 2.3 anywhere to download. Alas, nothing worked right. Eventually, I had to uninstall and reinstall everything. I still can't get Mega-POV to show up in the menu. (It did before.)

Maybe I'm just not putting Mega-POV in the right place, but I've tried many possibilities. Exactly where does your Mega-POV extension reside?

Fay

[davidjperdue]

Fay,

I have my megapov.exe here:

C:\Program Files\POV-Ray for Windows v3.1\bin

Also, I have the LPub 2.3 application in front of me - would you like me to send this to your email?

- David

[FayRhodes]

Yes, thanks. fayrho223@yahoo.com