Timeline for Generating properly-aligned shape from land survey description?
Current License: CC BY-SA 3.0
15 events
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| Jul 28, 2017 at 0:30 | history | edited | PolyGeo♦ | CC BY-SA 3.0 |
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| Jul 24, 2015 at 22:01 | vote | accept | Ginger Hawthorne | ||
| Jul 24, 2015 at 22:01 | answer | added | Ginger Hawthorne | timeline score: 0 | |
| Jul 21, 2015 at 23:46 | comment | added | Chris W | Now I will say that for permitting and construction, usually those kinds of descriptions must be tied to a survey control network - otherwise they're just as useless to the municipality as they are to you. You might contact the county Building, Planning, Engineering, or GIS department and see if they have their survey control network available. As GIS data or just a table, it could give you the lat/long or other system coordinates of all the points those permit surveys should tie to. Also a quick look at their online map/GIS shows they have a qq layer. Maybe you can get a copy. | |
| Jul 21, 2015 at 23:44 | comment | added | Chris W | It looks like FL is a mess. BLM data is only Legacy, not the new CadNSDI. The legacy BLM data is incomplete with only a small percentage of townships though it has qqs for all. The alt source has the townships BLM doesn't (and not the ones it does), but qq coverage is extremely spotty. The county source for Orange (based on permit link) has qqs for a single section in a single township for the whole thing (it's the ladesc layer btw). And there are obvious errors/gaps in data too. Getting the shape isn't really the problem - it's aligning it, and for that it's mostly what are you aligning to. | |
| Jul 20, 2015 at 22:24 | comment | added | Ginger Hawthorne | Oof. Thanks for the added info, Chris. I'll look into planar coordinates and see what I need to do to work with that. The PLSS grid I've found doesn't have quarter-corners, so I'll also keep digging to see if I can find something better there. But overall, it sounds like it's not going to be practical to convert these surveys into GIS shapes. It was interesting hobby project, but perhaps not worth pursuing too much further. | |
| Jul 18, 2015 at 19:13 | comment | added | Chris W | You'll also get misalignments between descriptions, where a) two descriptions will conflict on bearing or distance for the same line and b) bearing and distance in line won't match the PLSS grid you have. They won't be off consistently either (ie N line off a different angle than E line). And keep in mind the grid isn't regular - what you think the midpoint is by math calculation may not actually be. With the PLSS it's important to remember that set corners take precedence over math. North line supposed to be 2640 but survey measures 2632? It's 2632. | |
| Jul 18, 2015 at 19:07 | comment | added | Chris W | metes-and-bounds uses bearings and distances in modern descriptions, so no, they aren't different. As mkennedy says you need to enter descriptions in planar coordinates, which neither WGS84 nor NAD83 are. I typically use the appropriate state plane zone for wherever I'm working. The PLSS grid you have should already have quarter-quarters in it (second division level). Note that grid is only accurate (surveyed) at certain corners and calculated/warped to fit at all others. It will NOT match up precisely, and may differ depending on source - there is a disclaimer on it for a reason. | |
| Jul 17, 2015 at 0:57 | history | edited | Ginger Hawthorne | CC BY-SA 3.0 |
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| Jul 17, 2015 at 0:53 | comment | added | Ginger Hawthorne | Thanks for the questions. I've update the post with additional details. | |
| Jul 17, 2015 at 0:52 | history | edited | Ginger Hawthorne | CC BY-SA 3.0 |
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| Jul 16, 2015 at 16:57 | comment | added | mkennedy | From the OP's description, he has metes-and-bounds which is local, planar coordinates. Vincenty (geodesic) is overkill. @Marty What coordinate system is the PLSS section corners in? NAD83 (lat-long)? | |
| Jul 16, 2015 at 11:19 | comment | added | MappaGnosis | Looking at the picture, my instant gut feeling is a projection issue. I don't know about land survey permits in Florida but they might be using UTM (whatever the relevant zone for Florida is) for instance. Then you have the issue of that image and what projection it might be in, how well it was orthorectified and whether it has been draped subsequently on a dtm as that can introduce its own distortions. I'd expect the planning department for Florida State to specify (somewhere) the projection/CRS to use. | |
| Jul 16, 2015 at 6:05 | review | First posts | |||
| Jul 16, 2015 at 6:53 | |||||
| Jul 16, 2015 at 6:02 | history | asked | Ginger Hawthorne | CC BY-SA 3.0 |