Hydrostatic Equilibrium

In honor of Earth Day 2013 on April 22, this week's article will be all about new developments related to the entire Earth. And what an exciting time this is for that kind of planetary science!

Researchers at the Harvard-Smithsonian Center for Astrophysics (CfA) announced last week that they had discovered two planets orbiting the K sized star Kepler-62 that could be completely covered in water. Liquid water.

Why is this such a big deal? Normally the temperatures and lack of atmospheres in space prevent water, should it exist at all on that planet, from melting into its liquid form. For there to be any possibility of sustainable life and possible habitation by humans one day, liquid water must be present. And here are two planets who have nothing but oceans full of the liquid orbiting a sun a little bit smaller and cooler than our own sun. Granted, the size and distances of the planets indicate that there is a huge greenhouse effect in their atmospheres to keep the water from freezing, but it's still awesome.

There are some issues with immediate Earth to planet communications though. For one, the planets are larger than the Earth we love; Kepler-62f is 40% larger and Kepler-62e is 60% larger. Researchers are at this point are unable to determine the mass of the planets because their compositions aren't known. This means we don't know if this planet would have any raw materials needed for technology or even life to evolve, since all the rock and metal would be below the surface. It is possible that some life may exist under the ocean's surface, but there would be no fire or access to metals (the pressure would be too great).

Still, the idea that there are two planets in the habitable zone is very useful information for scientists. For one thing, it's the possibility of other life that drives us forward. Second, it could serve as a second home for us (once we get over the increase in gravity thing). Third, studying other planets is just cool. How often have we discovered a planet completely covered in liquid water? Including these two: twice.

Unfortunately, looking at the planets through the Kepler telescope is probably as close as we'll ever get. The planets orbit a start that is 2,700 light years away from us in the Cygnus constellation, so there's no way to get there quickly. If anything this means that we need to take care of the planet we have now because the closest rescue boat is almost 3000 parsecs away, and that's too far for us to be saved. What would Earth look like with only water?

On that note, we wish everyone a happy Earth week!

Building Virtual JHU

So, how do we make all those buildings you see in Virtual JHU? Here's a quick run-down:

The primary 3D modeling program we use is Google Sketchup. Sketchup is convenient for a couple reasons. For one thing, there's a basic version that you can download for free. (Right now we're using the Pro version, which you have to pay for.) Unlike other 3D modeling programs, learning Sketchup is pretty easy, and it is remarkably powerful given how easy it is to use. The other thing that's nice about Sketchup is that it integrates very well with Google Earth, which is what we're using to present Virtual JHU. If you're interested in 3D modeling at all, I highly recommend getting started with Sketchup. Google has also come out with a tool called Building Maker, which is the quickest way to make buildings for Google Earth.

The first step for modeling any building for Virtual JHU is getting the floor plans. We are deeply indebted to the Office of Facilities Management for providing floor plans to us for Virtual JHU. Once we have the CAD drawings for each floor, we import them into separate Sketchup files. (The ability to import .dwg files is only offered in Sketchup Pro now.) We then pull up the walls outlined in the 2D floor plans to create a basic model of the floor, finishing by adding a floor slab underneath.

Once we have made models for each individual floor we stack them on top of each other in a single Sketchup file. Then we make a roof for the model based on photographs, first-hand observations, and (sometimes) measurements. At that point we've built a model that looks roughly like the real building (except very plain).

The next step is to begin photo-texturing the model. When we started modeling the buildings currently in Virtual JHU we took photos of each individual feature of the building (windows, doors, brick, etc.), used Photoshop to crop them, and then positioned them on the model in Sketchup, tiling materials like brick and marble siding as necessary.

This process resulted in models that were high in detail, but also in file size and are a drag on users' graphics cards. That's one of the reasons we have to continue to work on increasing the performance of Virtual JHU.

To help with performance, one of our programmers wrote a script that removed interior geometry from the Sketchup models, enabling us to present exterior-only versions for all the buildings (until you "open up" a building to see its individual floors). The script caused some issues with some of the models, damaging their materials. (You can notice some pretty significant issues with some of the buildings.)

To solve this problem, now once we have a building stacked we create a shell made of simple planes, on which to apply the textures. This reduces the geometry in the exterior-only versions of the models without having to use the "gutting" script. We have also been trying to use lower-resolution imagery that isn't quite as detailed.

So there you go, that's how we make our models in a nutshell. I'll leave other parts of Virtual JHU to another post. If you have any comments or suggestions, we'd love to hear them.