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I am taking pictures with a drone and I need ground control points (such as this) for rectifying the images. I used standard vinyl to make the checkerboard pattern. It is terrible. It is reflecting way too much light, especially the white parts, which makes the pattern not visible (a big white bulb is seen). What do you suggest?

First of all I am going to replace white with red. Then, should I get matt vinyl or should I use a permanent matt spray on top of the glossy vinyl? Or is there any colored matt spray? Just remember I need it permanent, these things are going to be outside under the sun and the rain for weeks. The glossy vinyl held perfectly outdoor, just too shiny.

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    I think this question would get a better answer over at GIS.SE where they have questions such as UAV Image collection Procedure and Georeferencing Photos With No Spatial Reference?. Even Physics.SE might be better. The article: "GCPs v. PPK/RTK: Which is Best ...?" says you can't just use GPS to place them. – Rob Oct 2 '18 at 12:44
  • Can't really tell from the picture, but the target looks small enough. I don't know for sure, but I would think concrete/colored concrete w/ a matte sealer would be decently non-reflective and would withstand the elements for a good while. – OnBreak. Oct 2 '18 at 15:37
  • Why use red rather than a neutral? Monochromatic colours focus at different points from each other and neutrals. You might want to avoid anything that introduces sources of variation. – Stan Oct 2 '18 at 19:42
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Else

Probably the optimal target would be neutral in hue, dimensionally stable, durable, weatherproof, easily made and replicated, etc.

Materials: I would suggest a 2x2 arrangement of 6" square ceramic tiles.

Colour: Rather than red, I recommend a mid-grey (to compare with a standard 18% grey card) and black. A grey shouldn't "bloom" but fall right in the middle of the luminance range of the subject (the earth). You can use it to set your exposure, even yet already.

Just a suggestion if you don't need white and black.

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