Technical Ramblings

Is OpenLayers Kool-Aid for developers? Not quite, according to Andrew Turner:

OpenLayers is more like “Here’s some sugar cane: Make something with it.”

— IRC

I’m leaving soon for an island vacation, to Grand Cayman after researching for tropical places to visit and browsing around. I won’t be back until Feb 24th.

In the meantime, I want to know what killer apps people have in mind for OpenLayers. What should someone build with it? Why? How would it help OpenLayers, and how would it help the world at large?

See ya’ll on the flip side.

I’m in DC on Wednesday morning for a meeting: Flying in tonight, arriving around 6, staying at the Holiday Inn in Reston. If there’s anyone who I should be stopping over and having a beer with tonight, let me know: at the moment, my plan is just to wander around DC monuments for a couple hours tomorrow night, since I Haven’t been able to find anyone I should be meeting. (I’m booked until my plane leaves on Wednesday; the trip is not about seeing DC, just a quick hop down for work.)

So, today, I built a small application to demonstrate the use of the accelerometer built into the Nokia N95. I decided to convert a simple example: the ‘ball.py’ example that ships with 홀덤사이트 Nokia’s distribution of Python for Series 60 (SourceForge).

The ball.py example uses the arrow keys to move a ball around the screen. Instead, I wanted to tilt the screen to do it.

The result came out reasonably well: I even used the webcam on the eeepc to put together a little video:

The code is available from my Symbian page, which has received so few changes that it doesn’t actually even mention my 6600 that I got years ago, and have since upgraded from.

In my searches, I wasn’t able to find a lot of source code for pure-Python scripting using the accelerometer, so hopefully if anyone is looking for demos of accelerometer usage, they can take this as an example in Python.

Love to hear any feedback if anyone else gives it a shot…

A couple utilities I was surprised to see in their current state on the Eee:

• host
• bc

Of course, installing extra packages isn’t hard: the eeeuser wiki has fine instructions, and I’ve already installed both utilities, but I was somewhat surprised that it wasn’t there by default.

Similarly, I was surprised that when I ran ‘cal’, the date was ‘highlighted’ (in reversed font), since that doesn’t happen on my stock debian install.

I just used the EeePC straight through for the first time, from a full battery (charged overnight) to a dead battery. Total time was 2h48m.

During that time, I was using the computer in what I consider a reasonably typical manner: reading news aggregator, chatting on IRC, working on OpenLayers. I ran the OpenLayers tests — which are a 100%-of-CPU chewing machine — two or three times, so there was some significant CPU usage in there, and I was also doing things like playing “Crack Attack”, so this wasn’t a ‘practically idle’ machine by any stretch of the imagination.

This seems reasonably in line with the advertised 3.5 hour battery life.

Unfortunately, the ACPI support for the laptop is really poor: the battery life is reported as ’40mAH’ at the moment, which realyl means ‘40%’, and it only moves in intervals of 10%. Quite annoying when trying to do any serious determination of the current rate of usage of the machine.

I think a big power sink in this case is just the fan: when I started doing the OpenLayers tests, the fan turned on, and it didn’t turn back off. I don’t knwo if this is just poor ventilation in how I use the laptop or what, but I assume that having a motor running will significantly affect battery life. Of course, the fan is presumably neccesary to stop the CPU from melting down, so turning it off isn’t exactly an option 🙂

JOSM is the ‘advanced’ OpenStreetMap editor, used by most technical users of OpenStreetMap. It is written in Java, but despite that 😉 it works reasonably well. Jokes about Java aside, JOSM is an excellent example of the type of ‘advanced’ editor that most GIS professionals would feel comfortable with* after some work understanding OSM: it has familiar interfaces for drawing lines, displaying and editing attributes, etc.

It works well on the eeepc: Java comes pre-installed, so it’s simple to get started; just download josm-latest.jar from the josm homepage and run (from a terminal) ‘java -jar josm-latest.jar’. You’ll be presented with a message that you can’t read, but it’s not really important. (The reason you can’t read it is that the message is apparently laid out with ‘fixed’ border sizes of ~350px… meaning the message only has about 100px across on the eee’s screen. “Oops.”)

First, we’ll set up the interface so it has more room for attribute values on the right hand side, by hiding the command history (Alt-O) and the selection list (Alt-E). You can bring these back at any time using the same shortcuts.

Next, we’ll download some data. The easiest way to download data for an area you’re interested in is to navigate one of the ‘slippy maps’ that OpenStreetMap has: my personal preference is to use Information Freeway, since it has a full page map. To see the area I’ve been mapping in, check out Grand Cayman; you can use this URL in JOSM by copying it, then selecting “File”, “Download From OSM”.

Navigating the map once you’ve downloaded it isn’t too difficult: by default, you’re in ‘zoom’ mode, which will do a ‘rubber band zoom’ (As we call it in OpenLayers) by default. You can switch modes using hte keyboard: simply hit ‘s’ (for select), ‘a’, for add, ‘d’, for delete, or ‘z’ to go back to the default ‘zoom’ mode. Moving the map can be done with Right click->Drag, and the arrow keys can also be used for navigation if you hold down ‘Control’. Zooming in and out can be done with the ‘scrollwheel’, which on the Eee is the right hand side of the trackpad.

In general, the editing experience of JOSM on the eee is actually significantly better than my mac. The reason for this is simple — the Mac doesn’t have a right click, which means that navigating by dragging the map doesn’t work. Additionally, one of the ways to get information about nodes near your cursor is the middle click. On the Eee, this is as simple as tapping two fingers on the trackpad.

That said, there are some significantly lacking aspects in using JOSM on such a small screen that don’t come up on the Mac:

• Toolbar is too tall — can’t select buttons towards the bottom of the list
• Preferences dialog is too small: can’t see the ‘okay’ button, so can’t enable plugins (one of the coolest aspects of JOSM)
• Inability to resize right hand side control panels: this means that the ‘layer switcher’ panel is as tall as the tags panel, which isn’t really neccesary for me. Similarly, ‘relations’ (Which are seldom used, at least at this point) share equal play time with tags/attributes, which is somewhat unneccesary

All in all, JOSM doesn’t work out too bad on the EeePC, but the lack of plugins due to the preferences panel being ‘too tall’ is somewhat annoying, and I haven’t yet figured out how to get around it. It’s possible that installing the plugins manually will work okay, but it’s been so long since I’ve installed them from within JOSM that I don’t even know how anymore!

* Of course, many GIS professionals working with OSM are going to have a steep learning curve, due to the nature of OSM’s data model: the majority of the vectorization software (at least, the stuff that I’ve seen) works with features, whereas OSM is topological, which makes interacting with the data a very different experience.

Got my EeePC. It’s so tiny! I love it already; I haven’t even pulled out the macbook tonight. (I’m sure this won’t keep up forever, since there are some things I really can’t do on a screen this small.) I did some playing with OpenStreetMap editing with Potlatch (painful, but not horribly so), figured out how to get a terminal up and running (ctrl-alt-t; handy), got subversion installed after setting up some extra repositories based on instructions in the eeeuser wiki, etc.

I will want to see if I can start building some tools targeted at the small screen resolution in OpenLayers or what have you, so that I can edit maps more effectively, and do other things like hook up GPS traces. I’m leaning more and more towards building myself some nice custom UIs for editing OSM, just to figure out how to do things that work well on my hacky platforms.

I have no plans (for the time being) to switch away from the ‘friendly’ interface, which seems (to me) to work just peachy keen. I am happy with my decision: even if I only use this thing intermittently from today forward, it’s a worthwhile and nifty toy to have, and I’m liking it a lot.

Just bought the Eeepc… should be here in a couple days. (It’s only coming from NYC via UPS Ground — since Boston is so close, maybe it’ll be here before the weekend…)

I’m going on a trip in a couple weeks, and wanted something I could do mobile mapping on without bringing my big, clunky laptop with me. I started looking at the EeePC, and bumped into the CloudBook — 30% longer battery life, 30GB hard drive instead of 4GB flash drive, same price point. It’s sold through Walmart, which is a major downside, but I might have been willing to accept the moral qualms that came with…

Until I found out that the trackpad is the little rectangle in the upper right corner of this picture on Flickr.

I want to do mapping with whatever I buy, and that little thing is simply not going to cut it. EeePC it is, if anything…

I’ve asked $Coworker to bring his in today to see if it’s really the right size for me: I’ve seen his before, but only for a brief bit, and want to get another feel for the size before I go with it. I’m hopeful that if I do this purchase, I can make the Eee something I can take with me everywhere *instead* of the Macbook — so vacations, etc. aren’t besotted by me pulling out a gigantic Apple laptop, but instead a little thing that is designed more for the ‘on the go’ case — and especially something that I won’t be trying to do work on, so that I’m not working during vaccations so much. 🙂