Datum / Projection Problem

[bwheelerZ42T5]

I thought I would post this here even though I am using Civil as I thought there would be more expertise in this forum.

We can receive images from a government web site that come in georeferenced. We usually can use the MAPIINSERT command to bring in geotiffs within Civil.

The site gives us a datum / projection of WGS_84_Web_Mercator_Auxiliary_Sphere

In the are that we utilize these, we use UTM Nad 83 (zone 10).

When using the MAPIINSERT commend the image is nowhere near the site coordinates and doe snot have recognizable coordinates of any sort.

Why can Civil not re-project this to the project coordinate system?

(I know there is a way to correct this in DataConnect by changing the datum / projection In the connection for raster but that is not practical for our needs).

Thanks in advance.

[ChicagoLooper]

There are many variables to georeference an image accurately.

1. Verify the native coordinate system of the image is WGS84 (EPSG 3857). If the native CS is mis-identified, your image won't insert accurately. (BTW, WGS84 based Mercator, spherical formulation, has units of meters, not feet. This means your drawing distances and dimensions  will be in meters too so other objects you, draw, add, paste, insert, etc. will need to be in meters too, and if they're not in meters, then your drawing will need to 'adjust' them from their native units to your drawing environment, which as you alrady know, is in meters. The modelspace drawing units will always adopt, or inherit, the units of the assigned coordinate system, in your case UTM83-10 meters aka EPSG 26910.) If you want to draw in feet, then you'll have to assign a CS that has feet used  in its units.
2. Make sure the assigned coordinate system overlaps your area. The assigned CS in modelspace should provide the 'coverage' needed for your area. For example, if your site is in Alabama, don't assign a CS covering Nevada.
3. Many user errors occur when using MAPIINSERT due to not-knowing-what-the-command-entails-and-users-simply-run-through-motions nature of the command. An easier, more friendly, and highly intuitive way of inserting an image is to use the Data Connect Palette, also know as a Feature Data Object (FDO) connection. An FDO connection will display the modelspace CS and the native CS of the image. If the CS of the image is not understood or is missing, Unknown will be displayed. Unlike MAPIINSERT, unknown will 'signal' the user to manually enter the correct projection so it can be inserted accurately.

What is the source of your downloaded imagery? Website?

Do you want to draw (and create dimensions) in meters or feet?

[bwheelerZ42T5]

We work in metres (being north of the 49th and all).

The projection does overlay with the area of the site.

This is the portal we are using for this specific purpose (and exporting and image option once we have out data from their layers).

I see the wrong coordinates when the MAPIINSERT dialogue box comes up.

I tried the workaround of using Data Connect and it showed the same projection as I sent in my first post. I was able to modify that to a more 'generic' flavour of WGS84 in the Data Connect window and it came in where it should.

This is not viable since we would then have to add a bunch of drawing layers and do a draworder for only one FDO item.

It's almost like Civil does not recognize that ESPG code (???).

Any ideas?

[bwheelerZ42T5]

Forget the portal link:

https://maps.gov.bc.ca/ess/hm/imap4m/  (iMapBC)

[Pointdump]

Hi @bwheelerZ42T5,
MAPIINSERT won't transform an image, so unless the image and your drawing use the same coordinate system, it won't work. Instead, use Raster Tools IINSERT, or re-project the image in QGIS.
Dave

[ChicagoLooper]

Thanks for the link. Yes, you can export' images (e.g. geotiff) from that site. The projection, as per AutoCADese,  is WGS84.Pseudo Mercator, WGS based Mercator (spherical formulation) or EPSG 3857.

The MPAIINSERT command cannot TRANSFORM this coordinate system (the native CS of the exported geotiff). Using the Data Connect Palette (an FDO connection) you can accurately insert the image, but there's a 'catch.' 

The catch is the image's coordinate system, WGS84 Mercator, must be manually entered because AutoCAD is unable to read it on it's own. Once you've entered it, then the image will insert accurately into your modelspace which is using UTM83-10.

An alternative to using an FDO connection as shown above, is to insert the image using the Map3D Query toolset. A Query will successfully TRANSFORM from WGW84 Mercator EPSG 3857 to UTM84-10. The query workflow, however, requires more steps. 

[ChicagoLooper]

You can accurately insert you image using a QUERY.

1. Open a brand new, clean, out-of-the-box metric template. Assign the coordinate system known as WGS84 Mercator (EPSG3857). Using MAPIINSERT, keep the defaults and insert your image. Name this drawing SETUP.dwg and save it in your project folder, then close the drawing (SETUP must be closed or the query won't work).

2. Open a second drawing or use your 'working' drawing. Verify this second drawing has the assigned coordinate system UTM83-10 (EPSG 26910). Next, on command line enter MAPWSPACE=>>Select ON. The Map Task Pane will open. Make the Map Explorer tab the active tab. Drag the SETUP,dwg from the project folder and drop it onto a 'blank area' of the Map Explorer Tab. See image-1.

Image-1

3. The SETUP.dwg will appear under Drawings section. Right-click Current Query=>Define. See image-2.

Image-2

4. To build your query, follow steps 1 thru 6, see images below. After you've completed all steps, right-click SETUP.dwg on Explorer tab of the Task Pane=>Click Detach. 

Image-3

Image-4

Image-5

Your image will appear in modelspace. Turn on Bing Hybrid and compare your newly inserted image against Bing imagery.

[bwheelerZ42T5]

Thank you both ChicagoLooper and Pointdump for your replies and advice!

The bottom line is that Mapinsert does not re-project and that's the root of the problem.

(Pointdump) I have brought it in using DataConnect but there are more steps to take than I was hoping.

(ChicagoLooper) In the past I have used the attach .dwg and query for different purposes but I had forgotten it. Thanks for the reminder.

I think I would like to see if we can get and install RaterDesign that was made forthis function but this would mean convincing management.

[ChicagoLooper]

@bwheelerZ42T5 wrote:

>>The bottom line is that Mapinsert does not re-project and that's the root of the problem.<<

Unfortunately that's a little misleading. Does the MAPIINSERT command reproject? Yes, it absolutely does.

It's just MAPIINSERT cannot perform transformations on 'ALL' coordinates. It can, however, perform transformations on 'SOME' coordinates.

Example:

I have a raster with geographic coordinates:

LL83, degrees (EPSG 4269)

My drawing's modelspace is assigned a projected coordinate system:

Illinois State Plane, NAD83, East Zone, US FeeT (EPSG 3435).

I can add the raster using either (a) MAPIINSERT or (b) using an FDO connect. 

The raster, a map with native coordinate system using DEGREES is successfully placed in modelspace using State Plane FEET. the results of the two scenarios illustrated above are here:

1. Does MAPIINSERT transform from EPSG 4269 to EPSG to 3435? Yes.
2. Does the Data Connect Palette (FDO connection) transform from EPSG 4269 to EPSG 3435? Yes.

Attachment.

[bwheelerZ42T5]

I stand corrected but was quoting 'Pontdump'.

It's curious Autodesk allows Civil to transform some but not all datum/projections that  Map or Raster Design can perform.

[Pointdump]

Hi @ChicagoLooper,
Well I'll be! That's the first time I've ever seen MAPIINSERT transform. I stand corrected.
Dave

[ChicagoLooper]

Yes, thank you to the esteemed Mr @Pointdump.

You rolled up your sleeves and ran the exercise in post #9 to see for yourself. Kudos to you! Now the million $$ question is:

Why doesn't MAPIINSERT get 'confused' and treat the Lat/Long for example 45.25 and -83.75 as through those numbers were feet? The command has no way to consider the units of degrees. Imperial and metric units YES. Units in degrees NO.

Yes it can. MAPIINSERT can transform! It can transform from Lat/Long degrees to State Plane Feet!

[RobertRiley]

Hi @Pointdump,

I was looking for a way to get the online bing maps  in C3D to align with more precision when I discovered this thread.

What caught my eye the most was the image attached to the post.  I recognized it!  😲  It is my home town area which makes me wonder how someone in LV, Nevada managed to use that area image (an area that is not really known for anything) in a post?

It is also close to the area I am having issues with bing maps in C3D being slightly off (west and a little south) from our surveyor points (that are on the same coordinate system).   Is it a surveyor equipment export or C3D/Survey import issue.  I don't know, yet, still researching.

Rob

[Pointdump]

Hi Rob,
I don't remember how I got that image. Probably got it from another post. Just a coincidence that it was your home town.
As for your Bing mismatch, I've seen Bing off more than slightly. Your surveyor points are probably good.
Dave

[RobertRiley]

LOL and Thanks