Sensor page

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Revision as of 20:37, 21 May 2007 by Olly (talk | contribs) (Explanation of features)
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What is it?

It's a page summarising all the data collected on activity on the island.

How does it work?

There are sensor scripts in some of the features around the island, these sweep periodically and record the position of any avatars nearby (in a very similar way to a radar). When the sensors have saved up lots of data they send it to a database hosted in the real world. All sorts of crazy statistics are then done and a summary page give an overview of activity on the island. It is currently hosted on olly's server ( and will, hopefully, be migrated to something more stable soon.

Where are the sensors?

The sensors are strewn around the island ( They scan once every five minutes, so it is possible that you are online for 4:59 and then log off and it will miss you, equally so you could log on and be sensed in one second. It could also miss you if you wonder around a lot. With this in mind the sensors can be thought to have a temporal resolution of approximately five minutes and will underestimate the true activity on the island.

I like it that they only poll every 5 minutes: you could argue that if somebody visits for less than this time it's not a visit of any substance (though you'll miss people zipping around the island quickly). --Mark Cabaret 08:50, 12 April 2007 (BST)
The catch here (as Olly and I discussed the last time we met) is of course that someone could be in an area for 9mins 59 seconds and not be scanned. They could then go to another sensor area and end up slipping in during the middle of a scan window. In other words someone could be on-line for a while and purely by accident not get scanned. This is however unlikely and thus we're not too worried. I think we've agreed 5 mins is a pretty reasonable scan resolution, but if we could get simultaneous scanning done by the multiple sensors it would certainly help the accuracy.--Dan 12:08, 12 April 2007 (BST)

The data gathering process means that a senor could record you going past and save the data, it will not send the data to the data base until the sensor is completely full however. This means that if you are in an area that is not very popular then it will not show up in the data base for a long while (possibly weeks).

The sensors only have a range of 96m (thanks LL), and they can only sense upto 16 things (thanks again LL), so we have to go down the route of many of them all over the place.

Explanation of features

The date range is the range of data fetched from the data base, there are three options (last 24 hours, last week, ever), all of the plottings on the page will adjust themselves to this date range.

The bird's eye view of the island has an overplotting of circles where people have been. The heat map is under development and will show this data in a nicer way.

The data on the left hand side is a small selection of interesting stuff; unique visitors shows how many unique visitors have been there; the most frequent visitor is the one who has the most number of entries in the data base (usually trixxiee); the total combined time spent online asumes that each time someone is entered in the data base they can be assumed to be online for five minutes; the most popular place is based upon which sensor picks you up (they are all named).

The list of 'who' shows when the last time people were online.

The bottom left graph shows the number of entries in the data base with a one hour resolution. This plot is similar to cumulative time spent in world by everyone in that hour.

To Do


Double check to see if 16 results overloads the list. - It does, make an array that can handle 16 results.

Synchronize the sensors so they all scan at exactly the same time, so greatly improving resolution.

Make the sensors output at midnight if they have data and are not full, then never more than 24 hours behind.

Have the sensors check to see if data saved correctly, and if not email the data to someone instead (this can then be inserted to the database by hand).


Make the sensor locations update correctly.

Calculate a volume of scan radius as to calculate a coverage measure.

Get a better map (this one is from SchomeBase) - am currently trying to inntegrate with map api, but doesn't seem to work on the teen grid. I have asked linden about this, am just waiting for a reply.....

Have the map say what the different regions are called, so you can see what is the most popular area.

Sort the 'fairy' problem.

And pray tell, what is the fairy problem? --Mgaved 15:17, 10 May 2007 (BST)
If you click on Fairy Schomer it also gives you TibbyFairy's data, as I used a LIKE statement to save an extra line of code (lazy). A great spot by Dan, I would have never noticed this!--Olly 16:36, 10 May 2007 (BST)

Plot of visitors each day, can see trends over time that way.

Make the heat map key have 256 divs every time as to avoid gaps and issues when visitor numbers>256.

Host in my dept.

or maybe PeterT will get it hosted in IET? good to get it in the OU and backed up, accessible by somebody else in case you're away, etc... --Mgaved 08:51, 12 April 2007 (BST)
wherever it goes I feel it needs to moved inside the OU asap. The reliability really doesn't seem to be there at the moment. Is there any chance the right people can get together to make this a priority task? --Dan 06:57, 19 April 2007 (BST
Yes I agree, it seems to be getting worse and worse. What was it like when I was away? Is there any word on Cortez? If not I will try to get this put up in my dept when I get back (next week), and I will make it my number one priority :)--Olly 11:36, 19 April 2007 (BST)
Up and down, Olly. Often down for what felt to be a considerable time on at least three days (I'd log in and it would be down, I'd log in a couple of hours later and it would be down). --Mgaved 11:52, 19 April 2007 (BST)
It has certainly felt very unreliable, hence my request to tackle this as a priority --Dan 13:19, 19 April 2007 (BST)
I'm on this, should be up and running by the end of the week.--Olly 11:44, 1 May 2007 (BST)

Make page pretty.

I can take on the development of a page layout for the proposed features if it takes some of the work away, and helps speed us forward. --Dan 12:08, 12 April 2007 (BST)
I rather enjoy this side of things, I can quite happily sit in front of the tv moving things around for hours on my laptop :), thanks though. Any suggestions of further things to include of placement of stuff is more than welcome (in fact it is strongly encouraged!)----Olly 11:11, 13 April 2007 (BST)


Finish the heat map.

Scale the graph properly.

Two maps, one for ground level (upto 100m?), and one for sky activity.

: When I view the page in Firefox or IE the cumulative hours graph is drawn first then the sensor birdseye view is drawn over the top of the graph so I can only see half the graph. Is this just on my computer or is it a common issue? cheers --Mgaved 09:30, 19 April 2007 (BST)

Olly is aware of this, need a bit of page redesign. Remember though he's invited comments on layout so don't be frightened to suggest alternatives --Dan 09:45, 19 April 2007 (BST)
How's that? --Olly 11:36, 19 April 2007 (BST)
Nice one buddy! -- Dan

Make the names in the 'Who' list a hyperlink that queries the DB to just show that user's information.

Make a page for the staff too.

Title on the y-axis plot.

Colour scale for the map.


Musings/Suggestions (please do add to this)

When viewing the graph I don't see it all (some falls behind the map) and there are no numbers on the vertical axis. - Dan

Ah. That's me making stuff on a high resolution screen again :( What do you think would be best; making the graph smaller, or moving it? Any idea what to call the vertical axis yet?--Olly 11:08, 13 April 2007 (BST)
Vertical axis - what's actually being shown? Is it cumulative time spent online by students per hour? --Dan 15:06, 13 April 2007 (BST)
It's the number of entries in the table in that hour, so 10 could be 10 people in one place for 5mins then it stays empty for the rest of the hour, or it could be one person staying in the same place for 50mins. So I guess cumulative time spent online by students per hour does cover it pretty well. The heat map also shows the same thing.--Olly 15:20, 13 April 2007 (BST)

If on the heatmap black represents 0 counts, why is most of the island not black? Bit confused about how the map is conveying the message at present. - Dan :Well spotted, black is 1, will fix this.--Olly 11:08, 13 April 2007 (BST)

Hello Olly, is it possible for you to insert a sensor in Mars to see how many people are coming into it?Thanks! --Marsbar9 Schomer 19:35, 9 May 2007 (BST)
Already one at `Marsland 182,185,111` is this were you mean? --Olly 19:51, 9 May 2007 (BST)
Maybe it is :S sounds like right height - what do they look like?--Marsbar9 Schomer 20:04, 9 May 2007 (BST)
That would be telling :) Actually they are scripts put in random things, so you would never find it :) --Olly 21:43, 9 May 2007 (BST)
So is it one of my objects then? Im going looking :P --Marsbar9 Schomer 13:20, 10 May 2007 (BST)
Can I have the data please? Is there a way of getting it off here?--Marsbar9 Schomer 17:06, 10 May 2007 (BST)
I'd rather not start giving the data out, we aren't sure what we are going to do with it all yet, and I'm sure everyone will start to ask for it too which would be a pain. However, I do think that having the ability of just showing a specific sensors data would be nice, so I will implement that when I get a chance.--Olly 13:00, 11 May 2007 (BST)[]