State Plane, Aerial Images, what is going on?

[camptech]

State Plane.  Yah, should be full stop right there.  That in itself is a PITA.  Add C3D moving linework and I'm pulling my hair out.

Question:  After editing some point codes for some points in a survey database, I tell C3D to "Process linework..." to regenerate my survey figures.  But all the survey points and survey figures come into the drawing in the wrong place -- they are no longer overlaying the aerial imagery correctly.  WTF is going on?  What am I doing wrong?  Why is this so hard in C3D?

Backstory:

An urgent staking job came up.  Engineering job called out "state plane coordinates," but the engineer cautioned me -- "don't trust them... we had to rotate/scale/translate GIS images onto C3D aerial images."  OK, fair warning.  I pulled some Benchmarks from Denver's CCD BM database -- Colorado Central State Plane northings & eastings plus their benchmark elevations.   I plonked the GPS base station right on top of one benchmark and told the basestation "you are here" (ontop of a point with these State Plane coordinates) and to use a Colorado Central StatePlane coordinate system.  I shot two other benchmarks nearby and their locations (and esp. their elevations) checked well.

I then shot all my field observations.  I went back to the office and loaded the field data into C3D into a survey database.  C3D brought in the points, and drew some initial survey figures.  I edited the drawings settings and set the coordinate system to HARN/CO Colorado State Planes, Central Zone, US Foot.  I clicked on the Geolocation Tab and set the Map to "Map Hybrid."  And... nothing happened.  No aerial imagery.  I searched Google for aerial imagery problems.  I was logged into my Autodesk account.  So now what?  I created a new drawing.  Imported the points manually via [Home Tab] > Points > Point Creation Tools...  I edited the new drawings settings.  Chose Colorado Central State Plane Coordinates, US Feet.  Went to the Geolocation tab.  Turned Aerial Hybrid on.  Walla... aerial imagery appears and the points are on the correct block in Denver.  Yay.

I go create a new drawing (3rd one).  Open the survey database for editing.  Insert the database into the drawing.  Edit drawing settings & set Colorado State Plane Central CS, US Foot.  [ Geolocation ] > Map Aerial > Map Hybrid... and this time Aerial Imagery appears and the points are in the correct location (more or less).  WHY DIDN'T IT WORK THE FIRST TIME?  But it gets better...

The aerial imagery is off by approximately 10'.  So I go [Geolocation] > Edit Location > From Map and in the "Geographic Location - Specify Location (Page 1 of 2)" popup window, I pan / zoom the aerial window in to my job site, and I right click (on a corner of a building at which I had taken a GPS observation) and select "Move Marker Here."  I then enter the Elevation of that point in meters in the lower right corner of the window, and select [ Next ].  On the "Geographic Location - Specify Location (Page 2 of 2)" window, I select an appropriate Colorado Central State Plane, US Foot coordinate system, and again select [ Next ].  The popup window disappears and at the "Select a point for the location < xxx.xx, yyy.yy, z.zzz >" prompt I right click and select "Node" and then select the COGO point that corresponds to the GPS observation by that building corner. The aerial imagery shifts and now my gutter flowline shots and survey figures line up very well (to the resolution of the aerial imagery anyway) with the aerial imagery.  A control point I set is in a grassy area and not in the street.  Fabulous.

I do some editing -- using the 'cfp' autolisp routine to copy and explode the survey figures so that I can work with polylines.  I move the polylines off my survey figure layers and to the appropriate drawing layers (roads, curbs, sanitary sewer etc.)  Oh... look at that.  I have a point code wrong on a COGO point and that is way a survey figure was not drawn.  OK... Go to [ Toolspace ] > [ Survey ]  and click on [ Survey Points ].  Find the point in question... edit the Point description and correct the point code.  A few manhole point descriptors were wrong too, so I edit those so that those points will then to into the correct Point Group.  I click on the floppy disk icon to save my edits to the survey database.  In the drawing I isolate my survey figures and delete them (so that I don't end up with duplicates when I process the linework.)  Back in the Survey tab, I right click on the survey database import event and select "Process Linework..." and my missing manholes appear in the correct Point Groups... the missing survey figures are drawn, 

BUT...

ALL THE SURVEY POINTS AND SURVEY FIGURES ARE NO LONGER IN THE CORRECT LOCATIONS VIS-A-VIS THE AERIAL IMAGERY.  To make matters worse... my previous linework created from the survey figures the first time around are NOT OVERLAYING the newly drawn survey figures.

So... what has happened?  Are all my lines in the wrong place now?  WHY?  Or has my survey database been corrupted and my COGO points are now wrong?  Why the shift?  Why are previously drawn linework (e.g. copy & exploding survey figures) no longer lying ontop of the newly drawn & inserted survey figures?

What am I doing wrong?  Why is this so hard in Civil3D?

Is my work flow wrong?  Instead of screwing around with Geolocation and Aerial imagery and expecting Civil3D to do the correct thing (is that so much to ask?)... should I initially zoom into my job site with Geolocation, then when it is proximately correct

1. capture the area to a layer ( [ Geolocation ] > Capture Area > Capture Area )
2. Turn aerial imagery off
3. Move the Captured Aerial Imagery off to the side (so it is obviously shifted)
4. Do NOT mess around with [ Geolocation ] > Edit Location at all, but rather
5. move the "Captured Area" from Step 1 (and moved in Step 3) above by clicking on an easily selectable point in the image (building corners do seem to work fairly well) and snapping it to the correct COGO point.

???

This has only cost me four hours of non-billable time.  (I just can't see to billing the client for time lost to this wonderful software.)

/SMFH

[brian.strandberg]

If I needed the aerial map to be as accurate as possible, I wouldn't use the Autodesk Geolocation tools.  They are very convenient, and easy to access.  However, I don't think its really built with sub-foot accuracy I would trust.

I would obtain and use a GeoTIFF, or a TIFF file which also has the associated .TFW world file for location.  

I think you would be much happier with that setup than with the built in aerials.  Hope this helps.

[camptech]

Brian,

Although I am not really looking for "sub-foot" accuracy in aerial images... it would be nice when I set a control point several feet off the edge of a road... that that control point not show up in the roadway itself.  Just sayin'...

FWIW and while on the subject... can you recommend or suggest resources form where I might obtain such "GeoTIFFs" that you mention?

What is more disconcerting is when I "re-import" or "re-insert" points (and figures) from a survey database, that all previously drawn linework "shifts"... and is thus of no-use anymore.  I either have to spend time figuring out from whence it shifted... and shift it back... OR re-draw it all.  To say this is disconcerting and a major PIMA is an understatement.

[Pointdump]

Hi Stephen,
There's a lot of moving parts involved here. I'm not looking over your shoulder and seeing what you see, so I'm reluctant to guess what might be going on.
If you could show just one reproducable problem at a time, posting data and drawing, I'm sure the problem could be pinpointed.
Dave

[camptech]

Dave,

I appreciate your reply.  At the present time... I need to get out the door to go stake this thing for the client.  Depending on how my day goes... if I have time this evening, I'll see if I cannot duplicate the problem and post a step-by-step with some actual .dwg's attached.

Best,

--

Steve

[LucasHicks]

Shot in the dark, but are your survey database settings>units>Coordinate zone the same as your geolocation settings?

[camptech]

@dave -- I am able to duplicate the issue.  Will try to post some .dwg files along with step-by-step here's how to break things this evening.

@lucas -- that was a good shot in the dark.  No, Survey Database Settings were set to <None> for Coordinate system / zone.  However, when I set this to the same Colorado State Plane coordinate system and re-imported the survey database from the .txt file... nothing appears to have changed.  So... good guess, but does not appear to affect anything?