Saturday, May 20, 2006

Google Sketchup

Google has done it again. On March 14, they bought up a small startup software company called @Last Software. This company produced Sketchup, a 3D modelling tool and sold it for $495.00 per copy. On April 26, Google released it to the world...for free. I should say that you can still buy a professional version of Sketchup, but for the average Jill or Joe, the free version should do nicely.

Be is very addictive. The easiest way to get started after you
download your copy (around 20Mb) is to follow the quick video tutorials offered on the Google Sketchup web site.

We're planning an addition to the house to be built sometime this year. Basically, a 1 room extension, dimensions 14' x 20' (or 4.6m x 6.5m). So I got started, drawing this in Sketchup, just to get an idea what it might look like.

So far I'm up to version 13. Whether or not you can do actual final construction drawings using this, I don't know, the jury is still out on that. It might just be too finicky.

The neat thing is that you can drag the cursor all around and rotate your drawing every which way, see things from the top, the bottom, sides, zoom in for very close detail.

After you download and install Sketchup, you can download my
drawing as well. Amazingly enough, the whole drawing only takes up something like a 130 k.

Monday, May 08, 2006

Google Planimeter and Rain

Huh?? First of all, what's a planimeter? A planimeter is a device which allows surveyors, cartographers and other people with weird interests to quickly compute the area bounded by a number of points by setting the counter on the device to zero, then dragging one arm of the device along the outline of the area while keeing the other arm stationary. Once you come back to the original point, i.e. you complete the circle or loop, you can read the approximate area off the dial. Now, mind you, it's quick and dirty: I wouldn't use it to calculate the amount of concrete in a complicated structural component, as you're liable to have a whole lotta concrete left over. (Quick, where's the nearest pothole?). While working for MTO in the seventies, we used the planimeter extensively to compute monthly estimates on road contracts.

In doing research for converting Latitude and Longitude to UTM, I came across Jeff Poskanzer's web site ( While perusing his site, I noticed one item that piqued my interest: Google planimeter. It allows you to calculate the area for either large or small areas and anything in between, with a good degree of accuracy! How it's done, I don't know, but it sure is interesting. In short, it shows you a Google Map, you place points on it by clicking your mouse and when you think you've got enough accuracy, you read the total area displayed just below the map. Way cool!

So, there was a massive rainstorm in the US on April 29th and 30th (2006). From I copied the map showing the average rainfall expected for the area involved. Then, I used the Google Planimeter involved to compute the total area. As you can see, the area measured 1.292e+6 km2, which equals 1.292 million square kilometers (I only measured the 2 inch rainfall area.) 2 inches equals 5 cm. To calculate the total amount of rain:

1,292,000,000,000 x .05 = 64,600,000,000 cubic meters. That's 64 billion 600 million!

From, I got the actual situation as of about 7:30 am April 29th.