no datum no projection

Just a question:
Do the plans SAY that the brngs are SPC?
For years, I did SOLAR observations, and said BOB was SPC AR South Zone.
This was strictly a derivative of the central meridian, theta, and sun shot.
N

Dan~ I wonder if the CAD file was created with a another program? I know I set the values for projection and datum in Carlson, but I don't think ACAD is actually set. The points and drawing is in the right location in ACAD even though it has no system. Now... I am unsure of the US or Int Feet.

Dan Patterson, post: 398406, member: 1179 wrote: Why am I always getting CAD files from people where it's set to no datum no projection

That is the default, and not many people know that there is a setting for that. Nothing bad happens except that you can't take advantage of some functions. Functions which most people - and by people I mean licensed land surveyors - don't know exist.

Face it. A large majority of surveys are coordinated by dumping an ascii point file from the dc and going direct to CAD with it. And the manner that those points were collected is left up to the PCs discretion. You preach to the choir here.

Nate The Surveyor, post: 398409, member: 291 wrote: Just a question:
Do the plans SAY that the brngs are SPC?
For years, I did SOLAR observations, and said BOB was SPC AR South Zone.
This was strictly a derivative of the central meridian, theta, and sun shot.
N

Well it actually says it's NAD 83 and NAVD 88. Nothing more specific than that, but the coordinates certainly look like state plane. I think my hypothesis is correct. Something along the line of what Mark described is probably how it ended up this way.

Scotland, post: 398414, member: 559 wrote: Dan~ I wonder if the CAD file was created with a another program? I know I set the values for projection and datum in Carlson, but I don't think ACAD is actually set. The points and drawing is in the right location in ACAD even though it has no system. Now... I am unsure of the US or Int Feet.

From a big time NJ engineering firm. I would assume it's all C3D. I'd be very surprised to find out they were using something else.

Actually, I just noticed that it specifically states that I will be provided a CAD file to use for layout. That's a first - even though that's often what happens...just never seen it in print before.

I guess I will just use their coordinate system and treat it like a local system. Time to recon and do a localization on whatever I find.

Dan,

Talk to the Big Engineering firm and see what they did. Don't assume that because they are a Big Engineering firm they, or the person who did the work, knows what they are doing.

Tie in their control points, as far apart as possible. See if you get a scale factor of approximately 1.00 (ground) or very close to what your NJSPCS scale factor should be for the site.

New Jersey is a US Survey Foot State

It is completely possible to have points in state plane coordinates with "no datum, no projection".

I have rarely seen that setting used.

I get CAD files like this all the time, somethings I can just change it to the correct zone and everything is correct, others times after I change it to the correct zone, I have block and move the drawing to the correct place. I usually never have to rotate the drawing, it's about 50/50 if I need to scale it.

Dan Dunn, post: 398448, member: 911 wrote:
New Jersey is a US Survey Foot State

Oh I am aware! Wish everyone else was....that's where the error comes in. Given an origin of 0,0 everything could be off of GPS readings by a few feet.

I think I'll just localize to their control given the situation. It's not like I have to be on state plane for any reason. I have to layout the contract drawings on the ground.

The projection set to no datum no projection in cd3 should not effect the coordinates themselves, conversly seting the drawing up at SPC doesnt mean the coordinates you see are SPC.
I would need a more info, llh, nee, for the points,,,,,at a minium, then you know

I would not localize, i would occupy their control and use it as its stated, if that doesnt work then i would static some and see if its even workable

MightyMoe, post: 398477, member: 700 wrote: I would not localize, i would occupy their control and use it as its stated, if that doesnt work then i would static some and see if its even workable

If I check into it using GNSS and it doesn't match 83, then how would I use GNSS the rest of the time without localizing?

I mean I could move the whole drawing to state plane based on my observations, but I don't think I would do that. If anything gets revised I would have to move it again every time there's an update.

Dan Patterson, post: 398478, member: 1179 wrote: If I check into it using GNSS and it doesn't match 83, then how would I use GNSS the rest of the time without localizing?

I mean I could move the whole drawing to state plane based on my observations, but I don't think I would do that. If anything gets revised I would have to move it again every time there's an update.

They say its SPC, i would respect that, occupy the points and survey them. I would request their LLH numbers and epoch and anything they would send me including DC files.
I would use a base rover setup, see if the points work internally that way, if that fails, take static locations and analyze whats going on.
Last resort is to declare the control a rogue system and calibrate or localize....

Dan Patterson, post: 398418, member: 1179 wrote: Well it actually says it's NAD 83 and NAVD 88. Nothing more specific than that, but the coordinates certainly look like state plane. I think my hypothesis is correct. Something along the line of what Mark described is probably how it ended up this way.

Be careful that some thoughtless soul did not scale to the ground and not truncate the resulting coordinates. This is why friends don't let friends scale to ground without truncating. The meta data is always missing.

Rant off

Dan Patterson, post: 398406, member: 1179 wrote: Why am I always getting CAD files from people where it's set to no datum no projection yet the plans clearly state that it's on state plane coordinates? I guess they have their drawings setup that way with no datum, no projection, and international feet? What are they doing? collecting data with GPS in state plane and dumping it into this drawing?

I think that's a C3D feature. Maybe they have plain vanilla autocad?

Dan Patterson, post: 398406, member: 1179 wrote: Why am I always getting CAD files from people where it's set to no datum no projection yet the plans clearly state that it's on state plane coordinates? I guess they have their drawings setup that way with no datum, no projection, and international feet? What are they doing? collecting data with GPS in state plane and dumping it into this drawing?

I do many jobs on the grid and rarely set up the parameters in Carlson. Now, in TBC, no they are all set so when I export the final points to draw with. However all jobs sent to others have all CAD drawing parameters set so they don't have any question.