Online Maps with OpenLayers

Shared Maps

<DoRight> This isn't exactly along the topic, but I did add a open map of Catacamas to a blog - http://ElCaminoAlHogar.blogspot.com/

<rrosso> ok, here's what I have so far (from OpenLayers walk-through): http://www.publicdatapublic.org/openlayers_exercise.html

OpenGeo.org Examples

<seanhorgan> The opengeo.org examples are pretty straight-forward

<ndoiron> http://workshops.opengeo.org/openlayers-intro/index.html

A JavaScript console is an extension that throws a red flag if the JavaScript on your page derails, and shows you where the problem is.

<ndoiron> Firefox 4, you can do Ctrl+Shift+K. Less than that, http://getfirebug.com/

<seanhorgan> in the world of javascript programming/debugging, firebug is an essential tool to get very familiar with it

<seanhorgan> if you click on the little bug symbol on the bottom right of your firefox window, it should split the screen with the bottom half showing the firebug console

<ndoiron> click the Script tab, then the down arrow, to set JavaScript to Enabled

<seanhorgan> Google Chrome has a developer mode (ctrl-shift-j) that is similar

Grassroots Mapping : Who, What, When, Where, Why?

<ndoiron> went to open source conference at State Dept... they are quite interested in mapping

<DoRight> Get more resources for us?

<ndoiron> got to meet some of the people behind http://grassrootsmapping.org -- they go beyond satellite maps by flying balloons

<introvert> why?

<ndoiron> higher-resolution, more recent, and can be open-sourced

<ndoiron> they took great photos during the BP Oil Spill and now some of those are in Google Maps

<introvert> how old are the satellite images

<ndoiron> introvert: if you have Google Earth you can find exactly how old their images are... it can be a few years

<rrosso> huh, that's cool. do they use GPS hand-held devices, or rely just on their photographs?

<ndoiron> rrosso: they put thousands of photos online, and people vote on whether they're good quality... I will have to post a link to that

<ndoiron> then they use US gov or Google sat maps to line them up

<ndoiron> and "stitch" them together

<ndoiron> website to vote on photos http://mapmill.org/

<DoRight> Yeah, gorgeous fotos!

<DoRight> But if they use google data, does that keep it from being used in opensource?

<ndoiron> I agree, using Google would make it non-free. But if they're in the US they can use some USGS satellite maps which are free

Script not working?

<introvert> Wow the text of the script is full of "Â Â Â Â Â " on most lines along with the code.

<seanhorgan> could be a cut-n-paste problem from a rich-text editor (MS word, etc)

<introvert> it was cut and paste from jsFiddle to emacs and/or gedit

<introvert> cut and pasting into gedit and emacs both give me Âs

<seanhorgan> can you easily strip them out?

<ndoiron> I'm seeing online that it could be a UTF-8 issue

<seanhorgan> that's what I thought too...I've run into problems like that it was usually encoding

<rrosso> ok, introvert, I pasted a working local openlayers map into pastebin: http://pastebin.com/aaKUza23

<introvert> Phew, local now works for me!

Loading Maps through JSON or KML

<seanhorgan> I'm trying to host a page with a map that draws icons based on locations from a file

<seanhorgan> is it best to store the data in a json format?

<seanhorgan> i don't have a concrete example for you (yet), but I'd like to iterate through an array of points and plot them on the map

<ndoiron> it does have GeoJSON for input. Try that format or KML, which people can view in Google Earth

<seanhorgan> can OSM handle KML?

<ndoiron> OpenLayers yes

<seanhorgan> cool. so I can probably use that GeoJSON as input then

<ndoiron> This looks like the example for you to try: http://openlayers.org/dev/examples/geojson.html

Get Icon URLs

<introvert> I have one last q- how do I get the filename for icons?

<ndoiron> I don't know if this works in your browser... right click and you should have 'Copy Image URL' or 'Copy Image Location'

Post your own files

<rrosso> is there a way/place for us to post files?

<ndoiron> on http://p2pu.org/webcraft/node/12927/document you can attach files when you post a document

Attachment:

chat-text.txt

Online Maps with OpenLayers

Course Material

Chat 17 Feb 2011: Squashing JavaScript Bugs, Grassroots Mapping, Loading maps through JSON or KML