Update: Home-Brewed Ground Control Markers

By | May 25, 2020
Behold the GeoVelo Mark 1 – Mod 0 Ground Control Marker!
Click the image to enlarge.

In my original post I discussed how you could create your own ground control markers using a plotter and some vinyl. I said I’d update you on how well they weather. The photo above shows a fresh marker, hot off my trust HP Z5200 large format printer.

In my mind as I typed that last sentence I mentally pronounced the Z in Z-5200 as “zed.” I think I’ve watched too many British shows during our quarantine.

Ground Control Marker Weathering Test.
Click on the photo for an excessively large version.

In July, 2019 I nailed a GCM to a large tree stump in my backyard. In this location it is exposed to the full sun for most of the day, even in winter. The site is in Columbia, Missouri. And here we are blessed with energetic and rapidly changing weather extremes. Sure, the GCM is a little faded, curled at the edges, and covered in dust, but GCM 14 survived. Note how the washers and nails have rusted. My guess is that with a little soapy water the colors might come back.

My conclusion is that HP Opaque Scrim is some darn tough stuff and quite suitable for your DIY GCM project. Your mileage may vary.

Full Disclosure: I wasn’t given anything for the creation of this report – which may or may not have been kindly towards HP and their products. Like most people with a large format HP plotter I spend as much time cursing HP as I do singing their praises.

About the Author

You can view Chris Dunn’s third person singular CV here. Basically, he’s a geographer with a law degree, a bar card, and a kick-ass GIS workstation. Email me at Chris.Dunn@GeoVelo.com