+jeff35080 Posted January 21, 2003 Share Posted January 21, 2003 I have read explanations here for why I sometimes see giant fabric crosses on the ground. I now know that these deal with aeiral photography. Often, during my travels I run accross where giant L shaped drawings are placed on roadways. These generally are bright white, the legs are about 1' - 2' feet wide and at least 6' long and have a 90 degree corner forming a giant L. Do these marks serve as corners for aerial surveying/photography? Jeff http://www.StarsFellOnAlabama.com http://www.NotAChance.com If you hide it, they will come.... Quote Link to comment
Readymixer Posted January 21, 2003 Share Posted January 21, 2003 I have also seen these in the format of a large V which I assume is pointing to a specific spot. I recently noticed in my ATV riding some stakes on either side of the trail labeled 'Picture Point' with a big plastic X across the trail. The are did not seem fit for aerial photography because of tree cover but I assume that has to be what it's for. "Not only is the universe stranger than we imagine, it is stranger than we can imagine." Quote Link to comment
Z15 Posted January 21, 2003 Share Posted January 21, 2003 They are all for aerial photography. They ID the location of the survey mark on the photograph. They are at least 3 types that we used for highway planning etc. The 'X' , 'V' or a 'T' shapped. What was used was usually left up to the descrection of the survey crew. An 'X' was used when we could set it, the 'V' and 'T' were used when space was not available, like for instance painted them at the edge of the pavement so the survey crew did not have to be out in traffic. Often times we would just paint a straight line accross the centerline a specified distance apart down the road for scaling of the photographs for "photolog" plans where they used the photograph as the base plans. We also used white vinyl over black vinyl for targets out of hard surfaced areas, out in fields, in the woods etc. The larger the target the higher the filght. Quote Link to comment
+miuwu Posted January 21, 2003 Share Posted January 21, 2003 In addition to marking corners, they are used in aerial topography. Most developers of major subdivisions use this instead of ground topography. Quote Link to comment
+jeff35080 Posted January 21, 2003 Author Share Posted January 21, 2003 Thanks for the info! I often wonder how many people go through life without noticing things such as this. Even before I got interested in benchmarks I would see these weird marks and wonder what the heck they were. Every day is a learning experience and today was no exception. Once again thanks! Jeff http://www.StarsFellOnAlabama.com http://www.NotAChance.com If you hide it, they will come.... Quote Link to comment
+Kewaneh & Shark Posted January 22, 2003 Share Posted January 22, 2003 Like everyone else said, they're aerial control panels. Sometimes they're not crosses but also in the shapes of Ls Vs and Arrows. This question (OK... A very similar one) was asked in the Getting Started forum on January 9th, asking about this Wierd Thingy Keep on Caching! - Kewaneh Quote Link to comment
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