One of the biggest challenges when making an Image Plot chart with geo referenced encoding is getting the specifically geocoded boundaries of the image.
Our TS Team as have been able to successfully use the free application below to not only create images for the Image Plot, but to also get the exact geocoded boundaries of the image.
They have found this to be a fairly painless process so I thought I would share.
Step 1. Open Maperitive.exe
Step 2. Position your map where you want to be. You can zoom in and out, and resize the size of the window to specify the dimensions of the image you will be exporting.
Step 4. In the command line portion of the program type: dump-geo-bounds and press enter. Four geocodes will be generated. Copy them to notepad. Example:
How to read these numbers is like so:
(left, bottom, right, top OR West, South, East, North) where left is the minimum longitude, bottom is the minimum latitude, right is maximum longitude, and top is the maximum latitude.
Step 5. To export your image as a PNG choose Export To Bitmap from the Tools menu. It will be saved to Maperitive\output\
Step 6. Take the geocode information from step 4 and add it to your_image_plot.xml file.
<?xml version="1.0" encoding="UTF-8"?>
<!--XML content goes here-->
Step 7. Uploaded both your image and your imageplot.xml to a content folder and design your Image Plot Chart as normal.
The software can be found here
The program does not need to be installed, and can run from the directory it is extracted to.