Dave Karoly, post: 435221, member: 94 wrote: I use the Modifrickinfried conformal conic projection very often.
You are not alone.
😉
Loyal, post: 435220, member: 228 wrote: I suspect that my comment above is somewhat misleading.
Nearly every Project that I have worked on since the mid-late 70s was ??observed/calculated? in some form of LDP (Low Distortion Projection). Now that said, it does NOT mean that the data submitted to the client was expressed in the underlying LDP.
Project data (Coordinates) are always submitted in WHATEVER ??system? the client requests. That could be NAD27 or NAD83 Datum, State Plane, UTM, Mine Grid, Modifrickingfied whatever, OR in the underlying LDP.
IF a client wants a 100 acre (or 100 sq. mi.) Retracement Survey situated between 6,000 ft. and 10,000 ft. NAVD, expressed in SPC or UTM (NAD whatever), then FINE, that's what he/she will get. That does NOT mean that I am dicking around with several degrees of rotation, and 800ish ppm of ??scale? when retracing the original 19th Century Surveys (cuss I ain't).
In the interest of full disclosure, I don't remember working on a project ??smaller? than ~4 sq. miles since the early 70s, so my views on the use of informal 1000/1000/100 ??flat Earth? coordinate systems, is more than a little biased. I DO understand that there are MANY scenarios where spatial ??short-cuts? of that sort ??work? just dandy, and I'm OKAY with that. I just see too many ??larger? projects fouled up by surveyors carrying that mindset beyond the inherent spatial limitations thereof.
Just my 2-bits,
Loyal
In the late 90's the county purchased a unit from the company, a chicken bucket, at the time they were really high tech, but we had moved on to a "newer" set-up and liked the 4700's so kept them as bases.
The county wanted a state plane based coordinate system to do a road project in the extreme NE corner of the county which is the east line of a state plane zone. So per their instructions I set them up with a point which was the lat and long for the NE corner of the county by rule, not actually by location but it's an even lat and long, basically a quad sheet corner with a lat of XXd00'00"N, long of XXd00'00"W and the coordinates were scaled around it. In those days the geoid models were iffy, but this was a gravel pit, and gravel road job so we went with it, there are nice 1st order bench marks along the county road and they worked ok. Scale factors were small for the area being at the edge of the zone and low elevation.
A development company came along and wanted to use it also so I gave it to them and they did a vast amount of work off it in about 5 nearby townships. By then Geoid 03 was out and elevations were working even better with it.
I got a call from the development company and sat down with their engineers who were working on a pipeline, it looked weird to say the least, tilted, odd, I started digging into the computer file and it turned out they were using the projection and scale set up for the area two state plane zones from the new project. I remember inversing between two points along the line and there was 90' of difference from ground and grid, elevations for the pipeline project were +4000' higher than the county road project. Can't remember the bearing tilt but it was substantial and I knew at that time they were working in other states,,,,,,,,,,