Monthly Archives: January 2013

Sideband #47: POV-Ray 101

Sideband MachineBy all indicators (page reads, Likes, comments), most of my readers don’t find POV-Ray quite as interesting as I do. That’s too bad, because I’ve finally decided on a theme for this blog. It’s going to be all-POV-Ray all the time! Think of the fun we’ll have!

Yes, of course I’m kidding. Anyone who knows me at all (hello, have you met me?) would know better. Me, one topic? It is to laugh. Out loud. (Honestly, I don’t know how mono-topical bloggers do it.)

But I do promise this is the last post—for now—about POV-Ray. We’ll just swing by the gift shop, and then move on to other things.

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Sideband #46: POV-Ray 101

Take a seat!

Take a seat! (click for big)

As promised last time, my simple tour of POV-Ray continues with some examples a bit more interesting than an abacus stone or a box with holes in it. Time to move beyond a bunch of teal-colored spheres! (How about a bunch of hunter-green cones?)

I think it’s nice to have a place to sit while I lecture, so I’m going to use my digital woodworking set to provide a bar stool (and maybe a beer). The beauty of the virtual world is that , well, free stools (and maybe beers) for everybody.

Because I don’t just make a stool. I make a thing that makes stools.

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Sideband #45: POV-Ray 101

Sideband ElectrodeRecently I took you on a tour of a virtual theatre I “built” to help illustrate a post about light and color. It’s virtual because it wasn’t built with wood or metal or rock, but only with 100% natural electrons grown in the U.S.A. (free range; no pesticides or antibiotics).

I also showed you some smaller objects I built with the same tool: a freeware ray tracing application, called POV-Ray. The application is a “rendering engine.” It takes your design and renders it as a 3D image, complete with textures, shadows, reflections and a variety of other life-like effects.

Today I’m going to take you down into the engine room!

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Color Redux

Color DemoIn Monday’s post I started writing about light and color. I described how white light can be created by adding three primary colors (red, green, blue), and how mixing any two result in secondary colors (yellow, cyan, magenta).

I went on to describe how subtracting two of the secondaries gives you the primary color they have in common, and how subtracting all three filters out all color, giving you black. The secondary combinations are the negative of the primary ones (e.g. blue is “anti-yellow”).

Finally I touched on how color is the “pitch” (frequency) of light. X-rays, radio waves, microwaves and gamma rays are all forms of light.

Today I continue the topic by exploring some details and nuances.

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Sideband #44: CG Theatre

Sideband ElectrodeBack on my first Sideband post, I wrote that, “Sideband posts are miscellaneous thoughts that accompany the main thread of posts. Think of them as small paths that meander off the main road. Some branch off, go a short ways and die after a short while. Others are scenic trails that follow along the main road.”

They never quite achieved that vision, so this year one goal is getting Sidebands back on track with that original “mission statement.”

And I’m going to start with fun topic: computer-generated 3D images!

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Color My World

Color DemoThis is a post I began quite some time ago thinking it would be a quick and easy one, since it concerns a topic I know very well.

But—perhaps due to my own inability to be brief—it turned out to be more involved than expected. Maybe I just have a hard time leaving out all the details. In any event, I set it aside until I had more time.

Then I had an idea for making this post a bit more fun (at least for me). The problem was: I needed to build a theatre! You see, this post is about color and light.

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Dimensional Coordinates

you are hereThe maps you find in some buildings and malls have a little marker flag that says, “You are here!” The marker connects the physical reality of where you are standing at that moment with a specific point on a little flat map.

Your GPS device provides your current location in terms of longitude and latitude. Those numbers link your physical location with a specific point on any globe or map of the Earth.

But to fully represent our location, longitude and latitude are not quite enough. (We might be high overhead in a hot air balloon!) To fully represent our position, we need a little more ‘tude, but in this case that’s altitude, not attitude.

We need three (and only three) coordinates to completely represent our location in space. This post is about why.

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BB #18: Butt Heat

Brain BubbleOkay, so here’s a question that’s bothered me a long time.

If you sit in a chair for a while, stand up and then sit down again, you don’t notice anything unusual.

But if you sit in a chair that someone else was recently sitting in, the chair feels warm!

So my question is: why do you not notice your own ass heat, but you do notice the ass heat of someone else?

What’s up with that?

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Dear SciAm

Dear SciAmThis is a post I’ve had sitting on the shelf for when I wanted an easy one. I don’t know about other bloggers, but it takes hours for me to crank out a post. Some can take most of a day. (There are some where I spent days making graphics, and an upcoming one has work that took weeks! (You saw a glimpse in a recent post!))

The situation this concerns is long past. This is no rant, just a piece on a life change that surprised me a little, made me sad a little, and which doubly reflected the end of an era.

I could write this any time, but today I got another plea from Scientific American magazine. Again they beg me to come back. Again I won’t.

This, then, is an open letter to SciAm, a dear old friend with whom I’ve parted ways.

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BB #17: Pointers!

Brain BubbleThis may be the first actual Brain Bubble I’ve ever posted! The original intent was to provide a mechanism for sudden (short) thoughts I wanted to record or put out there. But the BB posts quickly turned into mini collections of thought bubbles.

But today I started trying to get into Immanuel Kant (again), and that naturally led to a bit of Wiki Walking.

It was when I got to the article about the subject-object problem that a sudden brain bubble burst!

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