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whereabouts

Sorta off topic.. Giant White Crosses

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This is probably slightly off topic, but I'm curious if anyone has seen these before. I should probably take a picure and post it. When I was in high school I was in boy scouts and we were hiking somewhere around the area. We came to a clearing and saw a giant X or cross. It was probably 5ft by 5ft painted white on the clayish gravel. That was the first one I've seen. A couple nights ago, I saw one painted in the concrete of the median to an intersection near my house. I think I've seen them here or there over the years.

 

I wonder if someone painted these big while X's to align satilite maps or coordinates? It definitely seems like something for people to see from the sky. Maybe for airplanes?

 

Maybe I'll take a picture and send it. Could be a local oddity..

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whereabouts,

 

Probably what you saw was a target for aerial mapping. These are used to provide ground truth so points on an aerial photo can be exactly correlated with points on the ground.

 

Sometimes they are painted on a paved surface. Other times I have seen them on grass, usually around an established benchmark, and made of a plastic material. Here is an example from station 31E7 (AI8520) in Howard County, MD. This one is T-shaped, rather than X-shaped, but the idea is the same. The station disk is located where the three pieces of (now rather weathered) white material meet.

 

-ArtMan-

55cfce7e-4597-4045-9125-c253431b4031.jpg

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We used several patterns for these depending on field conditions. The size of the legs were determined by the spec's for the flight. For mapping we used 4 ft leg targets (overall 8ft). 8 ft legs (16ft oa) for high altitude flights for route location determination. The amount of targets varied but often we would use them in clumps of 5, 3 along the c/l of flight and one on each side called wing shots. We had the determine X,Y and Z positions for all of them and all had points set dead center. They called this photo-triangulation because they did not need this on every photo.

 

Common patterns

T

+

V

 

For what we called photoplan logs we would paint 8 ft line across C/L at certain intervals that we laid out in the flied so they could scale, 1000 ft were what we used. They then took these photographs and made plans from them. People assumed these were for police aerial speed tracking but they do not do that in Michigan (costs a lot of $$).

 

aerialtarget.jpg

 

if you look top center you can see a sketch of the targets in our field office. No thats not me in those, summers interns who are now big shot surveyors and engineers

field%20oofice.jpg

Edited by Z15

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Z15's field photos are excellent! Where in the snowy peninsular state are those photos taken?

 

At our sign shop here in Anchorage AK, we slit 48" wide rolls of white tyvek sheeting (plastic paper - like the stuff FEDEX & Express Mail envelopes are made from) into 18" and 24" wide rolls for the local surveyor supply firm. I've seen these X-targets still staked out 7 years later next to survey points on highway projects where our firm's installed the highway signs - that tyvek sheeting is tough. It's a variant of the same stuff they wrap houses in before applying the final siding (or, in some cases locally, I've seen it applied as the apparent final siding!)

 

And, as noted in another thread, that tyvek sheeting makes an awesome logsheet, but it prefers to be written on in pencil... (I sometimes recycle mailing envelopes into micro-logsheets).

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Z15's field photos are excellent! Where in the snowy peninsular state are those photos taken?

 

UP

 

top photo @ Iron Mountain

Low photo @ L'Anse

 

<<More Photos>>

Edited by Z15

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Aerial mapping makes the most sense. Thanks. I was reading some other odd benchmarks page and saw something else interesting..

 

http://www.unm.edu/~creelbm/pages/benchmark/cross-1.jpg

http://www.unm.edu/~creelbm/pages/benchmark/cross-2.jpg

 

Description is on the next page about 3/4's of the way down. Supposedly these were used by U2's to get their cameras aligned.

 

http://www.unm.edu/~creelbm/pages/benchmar...ks_unusual.html

 

Who knows if it's true or not, but it's kinda neat. I wonder where it is exactly, I can't read what the gps or benchmark says. I see a Z 47 on there, but I don't know how to search for that.

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It's a variant of the same stuff they wrap houses in before applying the final siding (or, in some cases locally, I've seen it applied as the apparent final siding!)

Yeah, the several times I've been in Alaska, I saw more Tyvek siding than any other kind! <_<<_<

Kinda grows on you.... Whatever works.....

 

Also, anyone else remeber the old 5 -1/2 inch computer floppy disk Tyvec sleeves? They were great! Impossible to tear.

Edited by Klemmer & TeddyBearMama

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duplicate! duh! why can't you delete these?

Edited by Klemmer & TeddyBearMama

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I keep hoping to see an arrow from an aircraft beacon, and even have gone to several long-time-destroyed ones hoping, but so far no luck. In fact, I have only seen one actual aircraft beacon. They don't last long here in my area for some reason.

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Well, I found the one that Wily Javelina logged with his pictures. it is CZ2333 and located in PINAL County in AZ. There have been a lot of Geocachers logging this one.

 

And now the one we recovered is CZ1035. It was also in PINAL County in AZ, right next to route 84. It was exciting for us to have spotted this and been able to log it.

 

It is about as much fun to go find our log on a particular mark that we found! Just wait till you have logged over 600 and then try to find a "special" mark. ;):laughing:

 

Hope this helped...

 

Shirley~

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Wait till you get 1000 + and see how hard it is to remember that one.

 

Like the Columbus New Mexico Airway arrow.

Now what PID was that.

 

And the Beacon in Rogers,Arkansas that was there and now is gone.

Hmmm what date was that log.

 

Dial up takes forever to reload the list.

 

OH well if it's important I can find it.

 

OH yes I have seen many of them white crosses,Arkansas-Missouri.

X's ...there all in Texas.

T maybe for Tennesseeeeeee.

V for Victory.No that may have been NAUVOO.

 

I can't rember which one there by now.

So I guess it's tudalu.

 

edit spelling it was Columbus,New Mexico Airport arrow.

Edited by GEO*Trailblazer 1

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I keep hoping to see an arrow from an aircraft beacon, and even have gone to several long-time-destroyed ones hoping, but so far no luck. In fact, I have only seen one actual aircraft beacon. They don't last long here in my area for some reason.

 

Matt,

 

I know where there are at least two concrete arrows still in existence in PA and I have visited them both. AFAIK, neither have any datasheets associated with them, but one shows some possible signs of being upgraded to a beacon at one point, though if it was, it was subsequently removed. The other does have a triangulation station within about 50' of it.

 

Shoot me a note off-board if you're interested and I'll give you more details, pics, & coords if you're interested.

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These arrows are more interesting then giant plus signs. :(

 

I see there is one in the area which doesn't look like anyone has recovered or destroyed since it was put in (JU3678). There is also no description on it. B)

 

I sorta know this area too. We use to ride four-wheelers on the old dump that is just north of there. It looks like it's at the end of a public road according to Google Maps. I might try and go by that on the way to work next week. If the arrows are actually in line with the airstrip, it might be a bit southeast of where the coordinates put it. I wonder if that land has been changed. I think they dump the dredgings from the Delaware River there. That's not really something I want to walk around in too much. Might catch a case of cancer or something.

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