topic Re: CAD to GIS in Data Management Questions

CAD to GIS

deleted-user-Pi5x1UjkS2PY — Thu, 14 May 2015 13:54:38 GMT

I am importing CAD files (stores plans) dwf/dwg into our ArcGIS system. Everything seems fine on that front except that I would like it to come in at the actual size of the store. In AutoCAD we do not have any geo referencing to the file however I would think with it being drawn to scale that I should at least be able to bring it in at that same scale just not the right place in the world. When I bring these files in they come in much larger than scale. Any trick or tips on how to do that. I would rather not do any manual adjusting.

Thanks,

Michael

Re: CAD to GIS

GajBala — Thu, 14 May 2015 14:52:34 GMT

You have to do some manual work, it shouldn't take you long tho. You need to set control points for your CAD dataset in Arc using georeferencing toolbar. You can read more about it in the links below.

ArcGIS Help 10.1

Re: CAD to GIS

ChrisDonohue__GISP — Thu, 14 May 2015 14:55:51 GMT

To have it show up at the correct scale, one would have to lay it out in CAD in the same coordinate system as is being used in your mxd Data Frame properties. Most CAD drawings, however, are not done in coordinate systems that are commonly used in GIS. Furthermore, another complication is that most CAD is in a "flat world" - i.e. outside of their specific GIS add-ons they typically will not account for the curvature of the earth.

The practical implications of this is that even if the CAD file is laid out in the same coordinate system, if your store is large, the corners may seen a bit misaligned compared to what you would expect. I see this often with Developments - an engineering firm will send in a CAD file containing infrastructure plans and it will not cleanly mesh with the existing data in GIS. So typically it will still need spatial adjustment.

Chris Donohue, GISP

Re: CAD to GIS

RickeyFight — Thu, 14 May 2015 15:00:54 GMT

The way I deal with sizing issues for CAD files is, bring it in, then I geofeference the file using the Geofeferencing toolbar.

Re: CAD to GIS

deleted-user-Pi5x1UjkS2PY — Thu, 14 May 2015 16:34:45 GMT

Thanks for all of the replies. My application that I have been tasked with is kind of different. My goal is to bring my dwg files into ArcGIS and serve them up to ArcGIS Server. Then I want to use some drawing tools that will measure the area. More of a markup form. In order to get the area though I need it be have the CAD file at the right size so when I draw the box it gets the right area.

I'm not worried where in the world they are at this point. Currently mine are going to 0,0 which is fine cause I can always zoom to that spot but I would like for them to come in at the correct size.

A rough example

Measure Polygon Area and Perimeter

Re: CAD to GIS

RickeyFight — Thu, 14 May 2015 16:38:26 GMT

What you could do is draw a line with the exact length of the project or the side of a building. Then use the georeferencing tools to match that line to the corresponding dwg. That way you know that the drawing is has the right lengths.

Re: CAD to GIS

EricPieniak — Thu, 14 May 2015 16:59:07 GMT

Use the units command and find the units of each drawing. this to find the percent that you will need to enlarge each, based on the CS environment you are going into - likely meters or feet from the likely CAD default inches for architectual. If possition doesn't matter, just scale the DWG/DWF by the percentage amount you figured out into a blank drawing where you have set units to the same as your GIS environment. If some of your drawing are unitless, as they are many times, you can just change the unit to match your GIS environment and scaling should then become auto while bringing it in. This does sound like a units issue. There are several methods to bringing DWGs into blank DWGs that have proper settings set up. The now, old fashion xrefing method allows for scaling while bringing it in.

Re: CAD to GIS

deleted-user-Pi5x1UjkS2PY — Fri, 15 May 2015 11:00:50 GMT

I'm not much of an autocad person but when I type in unites into the command line for autocad this is what I get back. How do I proceed from here?

Re: CAD to GIS

deleted-user-Pi5x1UjkS2PY — Fri, 15 May 2015 11:47:22 GMT

So it looks like when I measure the length of my building in CAD it is 418 feet and when I measure it after bringing it in GIS it is 16493. So very close to 40 (39.46) times larger in GIS then in CAD. I did the same with the length and got 348 to 13676 (39.3). Not sure this helps much but as I find out things I think are clues I thought I would share in hopes somebody can help me with this task.

Re: CAD to GIS

RickeyFight — Fri, 15 May 2015 13:01:17 GMT

Watch this at the 2:30 min mark Overlaying CAD data. Step three: Georeferencing CAD datasets | ArcGIS Video

This will show you how to scale it down

Re: CAD to GIS

deleted-user-Pi5x1UjkS2PY — Fri, 15 May 2015 13:21:32 GMT

So I found this toolbar but it doesn't allow me to use it on a layer that was brought in using the arctoolbox "CAD to Geodatabase". I can use it if I just use the Add data button to bring it in but then when I go to share it as a service it I get a bunch of errors. Why is nothing easy?

Re: CAD to GIS

RickeyFight — Fri, 15 May 2015 13:26:54 GMT

So What I do is bring in the cad data

Position it where I want it with the georeferencing toolbar

Then I have a layer already created for it, I ctrl + c and then ctrl + v to paste it to that layer.

Then you can publish it.

Re: CAD to GIS

EricPieniak — Fri, 15 May 2015 13:45:09 GMT

The video is cool to where you could do the scaling in ESRI, once you figure out the percent to scale. Although, If you can set these DWGs properly, should eliminate scaling, just need rotating. If you can, verify with text dimensions someone may have labeled in the CAD DWG - the 418 you refer to, could be inches (I know, most buildings are bigger than that) – no units are defined. There are some variables in process for this, like if you can't manipulate the originals then this is where I was suggesting to setup a new blank drawing for each. If your drawings are unitless like the your screenshot shows, go ahead and start a new blank drawing, use command ADESETCRDSYS and set the coordinate system to what you are using in GIS – if you can change the original DWGs, and if all of your drawings have no CS set and no units set, you can actually use this prompt, bottom section of the form, to set coordinate system for all of the drawings, all at once, but I have found the units have to be set as well working DWG to DWG – maybe you can try leaving unitless while having the CS set and bring in to ESRI environment may not care about the units and only look to the CS setting in the dwg?? Going back to the blank drawing setup, if you go that route, after setting a CS, set the units to match the CS units. Then bring in one of your drawings – best way is through task pane/map explorer, but this would depend on version of AutoCAD/Suite – sure way for all versions: xref command, right click attach dwg, once the drawing shows in this list, right click on it and use “Bind”. Save this drawing and now ESRI should find the settings for this drawing and convert/project the DWG units as it brings them in to display. You’ve got inches, feet, and meters that these software have to deal with. You should get the proper results, without manual scaling, if you can confirm your lengths in the DWGs and ensure they have the proper CS and units set. Only other issue might be if you are working GIS in older CS that may require 2 transformations – the CS warnings ESRI will give you cannot be ignored, should be well understood what is needed for proper transformations.

Re: CAD to GIS

EricPieniak — Fri, 15 May 2015 13:59:41 GMT

16493/3.28084(feet in a meter) then divided by 12 (inches) = 418.92218

Re: CAD to GIS

deleted-user-Pi5x1UjkS2PY — Fri, 15 May 2015 14:39:13 GMT

Thanks to both of your for your help. I have a lot more control over the GIS side of things and understand it better so I'm going to try and head down Rickey's path.

I like where we are heading. The problem is that once I have my layer where I want it I still have the errors from above. I tried adding a new group layer and moving the files over to that and then publish to server it still doesn't like something.

How do you handle this? I know you tried to explain it but I'm not understanding it.

Re: CAD to GIS

RickeyFight — Fri, 15 May 2015 14:46:29 GMT

Michael,

Are you copying each layer in the CAD group to a separate feature class?

After you do, you should not get so many errors when trying to publish.

Re: CAD to GIS

deleted-user-Pi5x1UjkS2PY — Fri, 15 May 2015 15:00:44 GMT

Sorry to sound so stupid but can you walk me through how I would do this? Do you mean for me to export each (Point, Polyline, Annotation, Polygon, MultiPatch ) of these to shapefiles?

Re: CAD to GIS

RickeyFight — Fri, 15 May 2015 15:19:56 GMT

When I import cad I only use the annotation and line (you may need a polygon feature class)

I have two layers set up: the building_labels for the annotation (i have to import manually)

and they AshlandSchoolsFloorplan layer

I position my cad drawing (GS-3.dwg) to a location

In an edit session (I am editing AshlandSchoolsFloorplan)

I then turn off all but the polyline layer.

I select all of the polyline layer.

I hit Ctrl + c then Ctrl + v

I ensure that I am copying to the right layer

Turn off your cad drawing to make sure that the layer copied correctly.

I then will add all building labels from the annotation to the building_labels feature class.

If you need the polygon layer then repeat the steps above on with the Polyline turned off and the Polygon turned on.

I then will remove all cad drawings from the mxd

I then share as service.

Re: CAD to GIS

MatthewDuffy — Fri, 15 May 2015 15:50:04 GMT

It is not exactly in the spirit of the question as you asked it, but another potential alternative could be the CAD2Shp software solution. They have got a not obligation trial available for download that might suite your needs CAD2Shape: Convert AutoCAD DWG / DXF to ESRI Shape (.shp)

Re: CAD to GIS

ChrisDonohue__GISP — Fri, 15 May 2015 16:58:46 GMT

I'll second that. I've found CAD2Shape to be very useful in converting CAD. Of the several workflows available to convert CAD, CAD2Shape has been the most effective for me.

Chris Donohue, GISP