Update readme.

README.md

@@ -6,6 +6,8 @@ This folder contains code to display payload (and chase car!) position data in a
 
 ![ChaseMapper Screenshot](https://github.com/projecthorus/chasemapper/raw/master/doc/chasemapper.jpg)
 
+The general idea is this application is run on something like a Raspberry Pi (could be the same one that's running [radiosonde_auto_rx](https://github.com/projecthorus/radiosonde_auto_rx)?) and is accessed from a tablet or laptop computer via a web browser.
+
 For this to run, you will need the horuslib library installed. Refer to the [Installation guide](https://github.com/projecthorus/horus_utils/wiki/1.-Dependencies-&-Installation).
 
 You also need flask, and flask-socketio, which can be installed using pip:
@@ -33,8 +35,9 @@ You can then start-up the horusmapper server with:
 $ python horusmapper.py
 ```
 
-The server can be stopped with CTRL+C. Somes the server doesn't stop cleanly and may the process may need to be killed. (Sorry!)
+The server can be stopped with CTRL+C. Sometimes the server doesn't stop cleanly and may the process may need to be killed. (Sorry!)
 
+You should then be able to access the webpage by visiting http://your_ip_here:5001/
 
 ## Live Predictions
 We can also run live predictions of the flight path. 
@@ -50,6 +53,19 @@ You will then need to modify the horusmapper.cfg Predictor section setting as ne
 You can then click 'Download Model' in the web interface's setting tab to trigger a download of the latest GFS model data. Predictions will start automatically once a valid model is available.
 
 
+## Chase Car Positions
+At the moment Chasemapper only supports receiving chase-car positions via Horus UDP messages. These can be generated by the [ChaseTracker](https://github.com/projecthorus/horus_utils/wiki#chasetracker--chasecar_nogui) application from horus_utils. This application can also plot your position onto the tracker.habhub.org map, so others can see when you're out balloon chasing.
+
+Eventually support will be added to get car positions from either GPSD, or from the client's device.
+
+
+## Offline Mapping
+(This is a work in progress)
+By default Chasemapper is configured to use the online OSM and ESRI Satellite tileservers. There is also an 'offline OSM' entry in the map layer list (top right of the page), which attempt to gather maps from `http://server_ip:8080/roads/{z}/{x}/{y}.png`. I've been doing some testing with using [Tilestache](http://tilestache.org/) as a lightweight tileserver, serving tiles from mbtiles files. A guide on how to cache up OSM data for use with Tilestache is TBD...
+
+(If anyone has managed to get ECW support working in GDAL recently, please contact me! I would like to convert some topographic maps in ECW format to tiles for use with Chasemapper.)
+
+
 ## Contacts
 * [Mark Jessop](https://github.com/darksidelemm) - vk5qi@rfhead.net