heedaf Posted March 8 Share Posted March 8 I got GPS data from my lot I want to build on. Is there a way to scale it? Lot is 100' wide but the gps coordinates come in at 157' wide. Not sure why but all I need is the slope of the lot. Link to comment Share on other sites More sharing options...
Rich_Winsor Posted March 8 Share Posted March 8 100/157 = 0.6369426751592357 Multiply your gps coordinates by this number and they will be 100' wide. Link to comment Share on other sites More sharing options...
SHCanada2 Posted March 8 Share Posted March 8 If you have multiple points You probably want to take a subset that fit within 100ft. You could scale the elevation data if you are only given two points for 157ft. What exactly do you have? A question would be, did you get wrong GPS data for 100ft or did you get bigger GPS data that represents 157ft. And did you get more than 4 points Link to comment Share on other sites More sharing options...
heedaf Posted March 8 Author Share Posted March 8 1 hour ago, SHCanada2 said: If you have multiple points You probably want to take a subset that fit within 100ft. You could scale the elevation data if you are only given two points for 157ft. What exactly do you have? A question would be, did you get wrong GPS data for 100ft or did you get bigger GPS data that represents 157ft. And did you get more than 4 points Just got a gps app on the phone and walked the lot. Strange that it would be that far off. Around 400 points with the lot. I guess I need to go measure the lot to make sure it is 100' wide. Link to comment Share on other sites More sharing options...
heedaf Posted March 8 Author Share Posted March 8 7 hours ago, Rich_Winsor said: 100/157 = 0.6369426751592357 Multiply your gps coordinates by this number and they will be 100' wide. Is there a way to do this via software or do I need to manually do it? Link to comment Share on other sites More sharing options...
JiAngelo Posted March 8 Share Posted March 8 Pretty sure this isn't a scale problem. Phone gps apps are only accurate to +/-16ft radius. That's +/-16ft at each point you measure. The error distance grows if obstructions exist - trees, clouds, adjacent structures. The quality of the phone's internals affect this as well. If you stood on two points that you know are 100' apart and shot 157', find a third point that is a known set distance from the first two points. Best if 【1-3】does not equal 【2-3】 . Go out there with a 100ft tape and pick one. Calculate (Actual Distance) / (Recorded distance) values for points【1-2】, 【1-3】 and 【2-3】, if they dont all equal 100/157 then you can't scale. I would wager if you shot 【1-2】 again you'd get a different number. 1 Link to comment Share on other sites More sharing options...
SHCanada2 Posted March 8 Share Posted March 8 (edited) 2 hours ago, heedaf said: Just got a gps app on the phone and walked the lot. Strange that it would be that far off. Around 400 points with the lot. I guess I need to go measure the lot to make sure it is 100' wide. GPS do not give accurate elevation data(which is needed for slope), like not even close, I think mine might be accurate to 50ft vertically(absolute) and who knows on a delta between two points. I tried it a few years back and it was all over the place for the delta. Your better bet is a transit or laser at dusk ....once you determine where the property corners are at physically. or go old schoold with a water level I also have a zip level for when you do not have line of sight. ..or just ask the customer for a survey...or get one done. The cheapest way, laser level if you know where the property corners are Edited March 8 by SHCanada2 Link to comment Share on other sites More sharing options...
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