GEO TIF Imports Coming into Different Places

[ryan.garza93ZE8]

I Have recently been using a workflow to get Hi res Aerial Data from ARCGIS Webmaps to Import Into Civil3d however, The Geotifs are importing slightly differently everytime? We use a consistent coordinate System across drawings so it isn't that. Does anyone have any ideas on what could be happening?

Workflow 

Print GEOPDF from ArcGIS Webmap 

Convert from Geopdf to GEOTIF using QGIS ( Raster Conversion command )

Import GEOTIF to CIVIL3D using MAPIInsert 

[ChicagoLooper]

Hi @ryan.garza93ZE8 

Instead of taking your PDF from Webmaps to  QGIS, can you upload it to the Forum?

There’s likely a more advanced method than doing it through QGIS and all that other stuff. Your way looks like it taking unnecessary steps and that makes it inefficient. 

[Pointdump]

Hi Ryan,
In ArcGIS can you save the Webmap directly as a GeoTiff?
Have you tried >>>ArcGIS for AutoCAD<<<?
Dave

[ryan.garza93ZE8]

Here is the PDF Print from ARCGIS Webmaps  i use before bringing it to Qgis to do the Conversion to a GEOTIF

[Pointdump]

Ryan,
I've never tried the Conversion Method you used in QGIS. I use Export >> Save As...
In Civil 3D, before using MAPIINSERT, in UNITS set Insertion Scale to "Unitless".
Dave

[ChicagoLooper]

Hi @ryan.garza93ZE8 

Wynn Golf Club, correct?

I have taken your GeoPDF and was able to convert to Geotiff and insert into Map3D. I used a geospatial program named Global Mapper to perform the export.

Because the Geopdf has a PROJECTION (a built-in coordinate system) it should be respected. What does that mean? It means it should be inserted as a geospatial raster, not as a plain vanilla image. By exporting the GeoPDF to a geotiff you are maintaining the geospatial integrity of the image. How you insert that exported image into AutoCad can be OK, good, or best. The BEST way is the optimal way to insure the collection of neatly organized pixels, or the image, plops down in modelspace. 

There are conditions that must be established prior to insertion, including:

1. Make sure you assign an appropriate coordinate system. You wouldn't want to assign a CS in Australia if your site is in Canada. Or assign a CS in East Florida when your site is actually in Las Vegas, would you?
2. You must know for sure (no guessing allowed!) what the native coordinate system of the downloaded WebMap has when taking it to QGIS (or whatever program you use) to perform the export. This means the image must have a starting CS when it first goes inside QGIS and a CS when it comes out. <<The exported image will have a new extension and a native Coordinate System. You must be cognizant what that native CS is.>> The new projection doesn't necessarily have to be the SAME coordinate system coming out as had when it went in. Why? Because you can re-project the image. Re-projecting means you have personally gave the image a new native CS.

You able to re-project because YOU have the power. You are in control, not QGIS. If you fail to realize this power, then the newly exported image might get messed up, and if it gets messed up, AutoCAD can't insert it correctly. <<Make sure your exporting procedure doesn't use a DEFAULT Coordinate System, especially one that's used to re-project the image without your knowledge. If your workflow is using a default, then you are NOT in control.>>

To insert your uploaded image AFTER converting it to a Geotiff, I treated it as a georeferenced raster. Using the Map3D Toolset I used the Data Connect Palette to add the image. When performed properly the imager looks like this:

   

Bing Aerial imagery is in the background. The Data Connect Palatte, the Map Task Pane, and the Properties Palette are also shown. The CS assigned to modelspace is NV83-EF, aka EPSG 3421.

SPECIAL NOTE:

You might also consider the method you used to assign a coordinate system to your modelspace when you originally opened your drawing. Although many users do assign one correctly, some don't......and they don't realize they're doing it incorrectly. Don't be one of those. If an improper method is used to assigned a CS, the insertion of geospatial objects might get messed up.

[ryan.garza93ZE8]

Thanks for the alternate workflow Dave

I will try this and see what the delta is from my current method

It seems like the deviation I am seeing is between exports at different zoom levels from the web map 

as shown in the screenshot ( red is 1"=20, blue is 1" = 40 scale) there is a deviation between the two GEOTIFs

There is only around a .75ft difference here but in other areas, it can be significant ~3-8ft.

 

[ryan.garza93ZE8]

1. 
   

   There are conditions that must be established prior to insertion, including:

   1. Make sure you assign an appropriate coordinate system. You wouldn't want to assign a CS in Australia if your site is in Canada. Or assign a CS in East Florida when your site is actually in Las Vegas, would you?

   Our Files are Established in the NV83-EF Coordinate system (3421) and this is done prior to insertion of the GEOTIF. Most of our work is in Las Vegas/

2. ---

   You must know for sure (no guessing allowed!) what the native coordinate system of the downloaded WebMap has when taking it to QGIS (or whatever program you use) to perform the export. This means the image must have a starting CS when it first goes inside QGIS and a CS when it comes out. <<The exported image will have a new extension and a native Coordinate System. You must be cognizant what that native CS is.>> The new projection doesn't necessarily have to be the SAME coordinate system coming out as had when it went in. Why? Because you can re-project the image. Re-projecting means you have personally gave the image a new native CS

    When exporting from the map, there is an option to export the PDF in the desired coordinate system. i believe this is where the PDF gets its georeference. I don't think QGIS is projecting but is used to translate from Georeferenced PDF to GEOTIF for use in Civil3D.

   "You able to re-project because YOU have the power. You are in control, not QGIS. If you fail to realize this power, then the newly exported image might get messed up, and if it gets messed up, AutoCAD can't insert it correctly. <<Make sure your exporting procedure doesn't use a DEFAULT Coordinate System, especially one that's used to re-project the image without your knowledge. If your workflow is using a default, then you are NOT in control.>>"

3.  Can you expand on this? im not really sure what you mean here. Are Drawings Templates are set in the NV83-EF Coordinate system. How would I check if this was set correctly?

4. I will try using the MAP3D workflow you detail out instead and see if that improves the accuracy 

[Pointdump]

Ryan,
I tried just now to bring the PDF in directly to C3D. MAPCONNECT: nope, MAPIINSERT: nope, Raster Tools IINSERT: yup, works good. That will save the QGIS step.
Dave

[ChicagoLooper]

@ryan.garza93ZE8 

Excellent! When you create your PDF, you are giving it Nevada State Plane, NAD 83, East Zone, Feet. Then when you take it to QGIS it will 'read' the image's native CS correctly.

From the looks of things you are exporting the Geotif correctly.

If the Geotif doesn't land in the right spot in AutoCAD, then I'd suggest you look at something else, like the 'method' you used to assign a coordinate system to your drawing. If you don't assign it properly then a good image may not insert correctly.

On a side note, I'm curious...............do you have Near Map? Is it installed as a stand-a-lone?

[ryan.garza93ZE8]

Are you converting to a TIF before IInsert with Raster tools? Mine doesn't have PDF under the list of supported file types

[ryan.garza93ZE8]

I will need to troubleshoot the method used to assign the Coordinate system. I didn't make the template so I'm not sure how it was assigned.

I don't have Nearmaps installed but it is a layer supported on our Jurisdictions ARCGIS webmap. 

[ChicagoLooper]

@ryan.garza93ZE8 

Can ArcGIS Webmap export to a format that's NOT GeoPDF? Are any of those format rasters such as, jpg, jp2, png, tif, tiff or ecw?

[ryan.garza93ZE8]

These are the export types available. However I am not sure if they maintain their georeference

[ChicagoLooper]

OK, you can export to jpg.

I'm guessing when I say this........

When you select jpg, it will ask you whether you want a world file to go along with the exported image. You should select YES, I want one. The jgw or the world file, when it accompanies the jpg, will give it geospatial accuracy.  Both the jpg and the jpw must be in the same folder. They must also have the same name, only their respectibve extensions will be different. Try it to find out.  

[Pointdump]

Ryan,
Clicking on "All Files (*.*)" will allow you to select your PDF. This works with Raster Tools/C3D 2024. I don't know about other versions.
Dave