Pete, for an educator we offer special services here on the forums, at no charge! Post an Excel file with the data and the image(s) of your campus and we'll help you put it together. [If the kid's names are confidential give them student IDs instead.] I'll be happy to help.
I was working on something similar to show room contents, usage, etc for the College I work at. This article was what I started with:
We happened to have a good map file before I started. I used circles at each point as discussed in the article, and when you mouse over a room, the tooltip displays information for the room. Took a while to get all the rooms mapped, so if you have a large campus be prepared!
I have not finished it, but one of the issues I ran into was when zooming, sizes of circles changed and could sometimes cause problems. I made sure to locate the reference point right in the center of the room number that was on the map.
I know some people had talked about custom polygon maps filling the entire room, but that was too complex for me.
I know the other guys here know a lot more about this stuff then me, but if I can be of any help please let me know. This is one of the funnest projects I have worked on in Tableau.
While single point annotating can be useful, the main drawback is that the points lose perspective like you said when you zoom in and out. I faced a similar problem when doing my project. Polygons are definitely the way to go and are not as complicated as you might think. Here is a tutorial. http://kb.tableausoftware.com/articles/knowledgebase/polygon-shaded-maps
While this tutorial is useful, I found it a bit hard to follow at first because I was new at this. Here is the basics for what you need to make polygons.
2.Coordinates of at least 3 points to the polygon (otherwise you just end up making a point or a line if you only use 1 or 2 points respectively)
3.Point Order This determines how tableau connects the dots
Since you already know how to obtain coordinate points on a background ill skip that step and use coordinate (0,0),(1,0),(1,1), and (0,1) (You can pick whatever coordinates you like for this base on the geography of your floor-plan)
So the polygon data sheet should look this this
Polygon Name X Y Point Order Square-1 0 0 1 Square-1 1 0 2 Square-1 1 1 3 Square-1 0 1 4
Now you just drop [X] and [Y] into column and row shelf,
Then select polygon for mark type and drop [Point Order] into path
Then put [Polygon Name] into the Level of detail below the marks tray and that will draw you a square with those coordinates as corners
Now to add data to the shape "Square-1" you can either join this polygon sheet with your data sheet that has data you want to correspond to each shape.
Area Students Category Square-1 55 Tech Square-2 44 Furniture
This data sheet could be joined by [Area] to [Polygon Name] and the data would be linked to the shapes. Alternatively, if you are working in excel you could to a vlookup for you polygon data sheet so that you only bring in one table that isn't joined
For instance you could do this
Polygon Name X Y Point Order Students Category Square-1 0 0 1
Tech Square-1 1 0 2 55 Tech Square-1 1 1 3 55 Tech Square-1 0 1 4
and that polygon would have all the associated data that you have on your data sheet that you want to correspond to your polygon.
If you have any questions about polygons feel free to ask, I have practically been doing nothing put mapping polygons for the last month so I am more than happy to share what I have learned.
Let me stress again, polygons are NOT hard to do once you figure it out and they are so much better than individual points on the map for what you are trying to do with mapping specific areas on the floor plan. Give it a try, its easier than you think!
Thanks so much for your input. Your write up made me revisit the polygons. That is certainly the way to go for this type of project in my opinion. It also has me re doing my project!
Thanks for the write up. I too did not have any idea what I was doing in Tableau (and often still do not) when I started my mapping project, but have been becoming rapidly more comfortable with it. Thanks for your valuable input as it has helped not only me, I'm sure other in the future, and hopefully the original poster.