Been thinking of something more rigid and durable for setting targets in rural desert areas in place of the white vinyl film.stretched between wood lath and nailed down. The reusable ones sold by survey supply shops are about $20 each.
Anybody try using white corrugated plastic panels cut to the needed width and length. Home Depot has the material at about $10 for a 4' x 8' sheet which should make about 8 targets which is about $1.25 each.
Nailed down with 60D nails should be pretty durable.
Appreciate any thoughts. Thanks.
I used this type of material several years ago for marking column lines on the shoring walls of a construction project. The construction management firm wanted to have the column lines marked on the walls so they could tell where you were until the building started coming out if the ground. It worked out very well. They lasted about a year.
I've used tyvek with great success.
I've successfully used that. Reused old Real Estate house sale signs, held down with fence wire 'staples'.
Latter made to suit soil type. Extra long in soft sandy conditions.
I have set many thousands of aerial targets, often in desert areas. I use rolls of vinyl target material in the width needed for the project (usually 6" or 12" but also 9", 18" and 24"). I usually use 8" or 10" spikes (buy a 50# box at home depot or lowes) and rebar tie wire. Sometimes I get the spikes that have a spiral pattern on them for looser soil. I place the spikes at the corners and run the tie wire between them along the edges, sometimes running across the target in an X pattern on each leg as well. In softer soils I have also used larger diameter stiff wire (I don't remember the gage) instead of the spike/wire combo. I cut a piece at the appropriate length to form a U shape that will go across the target and into the ground a sufficient distance to not be pulled up. Most of my projects are military bases, and I go back to many of them every few years. I have found intact targets 5 or more years later in the desert.
I prefer to get ID's if possible, then my next preference is a painted target and finally a vinyl target. I did buy a pack of the pre-made targets (square), but have never used them. A lot of recent projects have been ID only because they needed to fly immediately upon contract award. That can be challenging. In the film days it was common to use power poles and fence corners for ID's, but in digital imagery they do not like those at all. Areas with stop bars at intersections are the easiest, those work for a whole range of imagery scales. But, it is critical to understand imagery scales and what can be used as an ID. Some things can be used at pretty much all scales, like the corner of a large concrete pad, corner of a large stop bar, etc. In the last few years I have been doing a lot of 3" imagery control, that can be more tricky. Here is something that can be used at a wide range of scales:
While on the subject, I wonder my people paint targets in areas where there are perfectly fine ID's all around. Here is a recent example. I used the tip of the left turn arrow, somebody very recently painted a target between the two turn arrows:
Here in an urban area stop bars, traffic arrows, and corners of concrete slabs make up 95% of my photo control points. The only time I paint targets anymore is when we need a specific target shape, size, and density for low altitude mapping of pavement to road design precisions.
I often wonder who is supervising crews that set a new panel close to a perfectly good turn arrow. Of, why a crew will spend an hour edging a painted panel so it is ever so perfect.
My favorite panel, if I have to set one, uses a simple template I cut out of heavy cardboard. I outline the template in black spray paint, set the nail and disk, then fill it with white spray paint. Fast and highly visible. In Tucson, no question that is my panel.
When I paint a target (either center of T target or corner of L target), I like to use block filler paint that comes in 5 gallon tubs. Thick, and lasts for years, but can't always find it. I can count on one hand the number of times I have used spray paint, it just doesn't do a good job on larger targets. It is OK for the smaller ones as shown by Bruce Small.
The last project we did aerials, we used sheetrock, our aerial company wanted 8' x 6" "+" targets, so we got 4 targets per sheet.
I also thought about using siding boards (Masonite?)but your idea sounds good.
White latex paint and a roller of appropriate width is easier than spray paint. You can use a tray or just dip the roller in the can and use the street for a tray.
In dirt I use a roll of white on black tape.
We got an upholstery shop to make ours. They are white vinyl 6" by 6' stitched together at 90 degrees with two grommets sewn on each end as well as one in the middle. We use 12" spike nails hammered in the ground thru the grommets to anchor it.
They fold up to take up very little space in the truck and it's an easy set up.
I agree with the photo I'd points. I would set a nail at the end of the turn arrow in case it was needed later for control. Jp
