Turning Height Maps into Contour Maps

One of the items I want for students to use in Marscraft is an actual, real world, physical map to write down the data being shed by the broken rover.

The Marscraft surface has been created using a height map of the Gale Crater on Mars, which is a greyscale image. Each pixel’s shading represents the surface height at that area. Black is the lowest point, and white is the highest, with all the shades of grey being a height in between.
Height Map of the Gale Crater
It was two functions within Photoshop. First I reduced the number of colours used in the height map using Photoshop’s Image > Adjustments > Posterize… This blends the areas into a smaller set of averaged colour groups. In theory, these new areas are within a certain height range.
Posterize Function in Photoshop
The second step is to find the edges of these contour blobs. Filter > Stylize > Find Edges This creates a line drawing, which is now our contour map for the original height map.
Gale Crater Contour Map
Changing the number of levels in the Posterize step varies the number of contour lines.

Next: creating the student worksheet.

Pozible: Rough Science LIFE at the Melbourne Fringe

Earlier this year I took Rough Science: LIFE to the Adelaide Fringe. Now I get a chance to show it in my home town. But before then, I am raising money on Pozible bring it to the stage in September.

I am updating props, and there are posters and programs I would like to print. Plus, I would also like to hire an Auslan interpreter for the final night.

There are a bunch of rewards for contributing to the campaign. It would be awesome if you helped out! Check out the Rough Science: LIFE! Pozible campaign page for more details.


The news of Robin William’s death floored me.

He influenced me. I named him as a role model in an RE class when I was in Year 10. I remember being inspired by his confidence.

In university, I taped an interview with him and Martin/Malloy, which I listened to over and over. The difference between their comedic styles was stark: Williams effortlessly made jokes about whatever subject they were talking about. It seemed to be the tip of an iceberg of massive eclectic knowledge of the world, powered by confidence.

All of this went into the hopper of what became my own stage presence. Robin Williams, Jim Carey, Rowan Atkinson, and Bill Cosby were my comedy touchstones.

Energy, wit and confidence. I remember the delight when I recognised Williams when I was eleven and singing along to Bobby McFerrin’s “Don’t Worry Be Happy” filmclip.

(Years later, I would do my own version of Bobby McFerrin’s pentatonic scale demonstration during my second Evening of Rough Science stage show.)

At some point, probably after Bicentennial Man, I stopped caring so much about the films he starred in. Good Will Hunting was the last film he was in that I connected with.

Now I suppose there will be newspaper and blog headlines: “The day the laughter died.” I’m sad, and I feel his loss. At time same time, I look back on my past, and see the moments when his presence in the world touched my reality, and I am glad he was alive.

Duolingo’s Être/Avoir lesson

So far in my progress with learning French using Duolingo, I have mainly need to focus on vocabulary. Now that I have got to the higher level lessons, I am getting into the meatier grammar. It has taken quite a lot of attempts to pass the Être/Avoir skill level. There was nothing for it, but to memorise the following:

être (to be)
je suis
tu es
il est
elle est
nous sommes
vous êstes
ils sont
elles sont

avoir (to have)
tu as
il a
elle a
nous avons
vous avez
ils ont
elles ont

(Pro-tip: if you want to type ê on a Mac keyboard, press option-i followed by e.)

The 360 Holographic Video Display That Isn’t

Image from Science Alert
The daily grind of looking for technology breakthroughs to report on must become struggling. Take for instance this report on a 360 Holographic Video Display I’ve seen now on Science Alert (This Star Wars-like 360-degree video can be seen from different angles) and CNet (Help Me Obi: Is this the first true 3D video?)

Video Objects from Helson and Jackets on Vimeo.

I found the effect that the inventors have created pretty cool and interesting. Though I was wondering to what extent that was a 3D image, as I found myself asking some questions:

1. Why is it in a darkened room?
2. How did they film that baby from multiple angles at once?

The second question was easy to answer: they didn’t. All the images being displayed in this demonstration are anchored in 2D.

The first question can be answered by looking carefully at the ‘medium’ that the images is being projected onto/into. It’s blurred. It’s dark. It appears to be transparent.

A comment on the CNet page pointed me in the right direction. I think it’s a piece of angled glass spinning at high speed. A projector is underneath pointing up, and the image you see is a reflection off the glass. Now it makes sense that it is a 360 degree projection: no matter where you stand in the room, you can see the displayed image. It also makes sense that the installation is in a darkened room. Too much light will wash out the image.

Like I said, the effect is cool. But I have reservations on how it’s reported, which brings me back to the Science Alert and CNet articles. Take this line from Science Alert:

“And besides looking amazingly cool, the 360-degree video object could have many industrial applications, including 3D drawings, computer assisted design, and mesh models” (Science Alert)

Yes, it does look very cool. But there are no industrial applications here yet. Even if you had a 3D CAD drawing, everyone in the room will still be seeing the exact same 2D image. Not a 3D image from different angles.

It got me thinking. You could get true 3D if, as the mirror rotates, the system projects a different image for each viewing angle. If you get the timing right, the viewing lines from different parts of the room will see different sides of the object. This would need quite a lot of processor power to render all the images on-the-fly. Or, have many pre-rendered images ready to project. The potential is there for true holographic 3D, but this prototype is not it.

In reporting a “new technology” I would encourage writers to think deeper about how stuff works. It will give the “future uses of this technology” part of their report more accurate expectations.