topic Re: Geolocation always offset from Bing maps in Civil 3D Forum

Geolocation always offset from Bing maps

ronald.tubman — Wed, 10 Mar 2021 18:22:59 GMT

Lots of Geolocation posts on here but I can't find anything that addresses my problem. Whenever we survey a new site we tie into state plane coordinates. When I bring the points into the drawing the map shows up as it should but it is always offset around 4' north from our points. We are using C3D 2016. Our settings in our GNSS equipment and the C3D drawing are the same (RI83F). I have asked our C3D reseller and our GNSS provider and neither could help. I have attached a drawing of a site so you can see what I'm talking about. Check out the pool and edge of pavement and you'll see it clearly. I have a feeling it's something small but it's driving us crazy. Thanks in advance for any help!

Re: Geolocation always offset from Bing maps

LucasHicks — Wed, 10 Mar 2021 18:53:44 GMT

Move the image.

https://www.youtube.com/watch?v=mk-y2Xa_K0M&t=3s

Re: Geolocation always offset from Bing maps

Pointdump — Wed, 10 Mar 2021 19:23:32 GMT

Hi Ronald,
Bing mismatch like that is very common. I've seen it a lot worse. The only way to fix it is @LucasHicks suggestion and link.
You might also see if your state has any imagery available.
Dave

Re: Geolocation always offset from Bing maps

ronald.tubman — Wed, 10 Mar 2021 19:50:13 GMT

Thank you @Pointdump and @LucasHicks. I've always suspected that Bing was the issue but it seemed so consistent I needed to make sure. I have already been using your suggestion @LucasHicks so I'm glad I was at least doing that right. Looks like I'll be contacting our state GIS people to try and get the latest aerials integrated.

Re: Geolocation always offset from Bing maps

sboon — Wed, 10 Mar 2021 20:45:59 GMT

If you know what the adjustment is you can make that permanent for all of your drawings by setting it in your template.

When you set a coordinate system Autodesk Map gets involved, and it changes the Transformation settings in your drawing. In your case they should look like this.

Copy the local values to the grid values, change the rotation to zero, and make sure that the Apply button is turned on. Now the Bing image should come in at the same location that it is currently.

Next step is the adjustment.

Play with the grid values until the image fits correctly. Open your template drawing, edit the numbers to match and save that file. From now on all new survey plans should match Bing.

Steve
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Re: Geolocation always offset from Bing maps

ronald.tubman — Wed, 10 Mar 2021 21:17:19 GMT

Now this I like! If I do this will it effect my survey info at all or just the Bing maps?

Re: Geolocation always offset from Bing maps

Anonymous — Wed, 10 Mar 2021 21:37:01 GMT

Rhode Island seems to have a very nice GIS department.

Here is a WMS for 2020 images.

https://maps.edc.uri.edu/rigis/services/IMG/RI_202009_RGB_3in_spf/ImageServer/WMSServer?request=GetCapabilities&service=WMS

You can connect to this using Map. (mapwspace - then connect to data) WMS is an option near the bottom. Paste the above into the URL portion then add to map.

No user name or password is needed. (just hit okay)

Re: Geolocation always offset from Bing maps

sboon — Wed, 10 Mar 2021 21:55:12 GMT

That depends on how and where you import the field data.

In Civil3d the North and East values you see in the drawing are assumed to be GROUND values. If you import points from a text file and your Import/Export format uses the default headings then the software assumes that file is also GROUND coordinates. Points in the drawing will match points in the file.

The coordinate display in Civil3d can also show you the calculated GRID values for points. Here's an example of a drawing that has a scale factor and transformation applied. Notice how the GRID values are very different from the GROUND coordinates.

If you import or export GRID data (and the Apply Transformation Settings button is turned on) then the transformation and scale factor will be applied as the data moves in or out of your drawing. If I was to export points from this file using a format that specifies GRID north and east then the text file would show those GRID values in it.

The other factor to consider would be if you use a survey database. Coordinates in there are generally assumed to be GRID. If you were to import a point file there and then move the data into your drawing with Transformation turned on then the GROUND points would be shifted. There are ways to get around this, but it depends on your workflow.

Steve
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