Ditch Assist can now import and display map overlays on top of the Google base map. This may be used to show cut/fill maps, drainage designs, aerial (UAV) imagery, or any other maps that the operator may need to reference. Due to the format requirements of the Google Maps API and the way it's implemented into the app, the requirements for map overlays are as follows:
- Must be in either .png or .jpg format
- Must have accompanying World File (.pgw or .jgw)
- Must be referenced in WGS84 geographic coordinate system (not projected or warped) - the original image should appear 'squashed' for locations significantly north or south of the equator
- Should be as small as possible to reduce memory use. Ideally under 5MB -
Please test outputs by loading into Ditch Assist app to be sure they load correctly and are displayed at the correct location on the map.
Samples are provided. These images should line up with the town of Oakville, Manitoba, Canada
One method to create image overlays in the correct format is to use Ag Leader SMS software to geo-reference and then export out a map file in jpeg format, or to export an existing map layer. Do do this follow these instructions:
Import and geo-reference an image then export to use as overlay in Ditch Assist (in this case we'll import a screenshot of a cut/fill map, geo-reference it using SMS, and export it to use as a map overlay in Ditch Assist to tell us our cut/fill zones):
- In SMS open a map showing the field or area you have a map image for. Then open Read Files > Generic > Image. Browse to the image to import and geo-reference. In this example, we're importing a screenshot of a cut/fill map in jpeg format
- A window will open showing the image to be imported on the left, and a map view on the right. Use the tool to click in 3 places on the map and the 3 corresponding places on the imported image.
- Finish importing the file by assigning it to the correct client, farm, and field
- From the management tree, right click on the image file you just imported, and choose Export
- Choose 'Export to Generic Format' > Image > JPEG and save the image to your hard disk.
- Open the location you saved the image to. You should see the jpeg image plus an additional text file with the same name - this contains the geo-referencing information in the format required by Ditch Assist. Copy both of these files to the tablet. When you add the image as a map overlay it will be displayed in the correct location right on the Ditch Assist map!