Surface from DEM - change path

[AllenJessup]

I have a Surface that was built from DEM files. Since it was created the path to the DEM files has changed. Drive letter changed, nothing else. Is there a way to update the paths to the DEM files or do I have to rebuild the Surface from scratch?

Allen Jessup
Civil 3D 2012 SP 3 / IDSP 2014
Dell Precision T3610, Xeon CPU 3.70 GHz
Win 7 Pro, 64-bit,32 GB RAM, Nvidia Quadro K4000
Samsung SSD 512GB
HGST (WD) 512GB drive

[jmayo-EE · Accepted solution]

With some surfaces, LDD I think, if you go into the surface properties, definitions tab. If you see an operation for the DEM, srcoll all the way to the right and try double clicking the invalid path. You may get the button to browse for a new location.

Not sure if this will work with a DEM.

[AllenJessup]

That does it John. I was trying to do it at the bottom of the toolspace. Thank you! It's a Surface of the whole County so I wasn't looking forward to recreating it.

Allen

[jmayo-EE]

HTH Bud. 🙂

[asankaHW]

Hi John,

Im faced with the same or similar issue, and im trying to understand where to double click to get this pop-out window, so that I can browse to the new location of this DEM file. 

Also, is there a way to break the link to the original DEM file and have a data on ts own saved just in this drawing it self?

Thank you kindly.

[rl_jackson]

Right-Click

[asankaHW]

Sorry, then what?

[jefflambert9091]

When you are in the surface properties, definition tab, you can see the file path under the Operation Type and Parameters. Click the folder icon far right to change the path. If you just want cad objects, change your surface style to what you want (contours, triangles, points), select the surface and use the "Extract from Surface, Extract objects.  

 

[asankaHW]

Hi Jeff,

This is great and thank you for the detailed explanation. It worked like a charm, so thank you.

One question though....., is it possible to break the link of these external TIFF files, so the data stays inside the drawing itself without any outside ties? I tried to export and import i as a Land XML, but once i import it there file became much larger, and there were no known data in the surface properties. Is there a better or a proper way? Just curious.

Thank you.

[jefflambert9091]

Depending on how accurate you need it after you extract the contours, you can "Mapclean" ( I have tried weeding the polylines and tried "PLdiet" but maplean does a better job and is faster) Then create a surface from those contours. After that you can them simplify the surface in the edits (use Edge contraction) to take it down more. I suggest you keep the DEM surface in the dwg and use different surface styles in different colors to compare how much the contours change.  

[asankaHW]

Hi Jeff,

Thanks for this.... great idea. My file size went from 76MB to 10MB. You rock!

Much appreciate your feedback and guidance.

Cheers!

Asanka

[jefflambert9091]

Glad I could help.  I sent you down that path because you were asking about getting the objects. There is another way that is a bit easier. Create a Surface, then in the surface definition you will see DEM Files. You can attach your file here. Then simplify the surface (edge contraction) from there. The danger with either way is hacking the surface too far and losing the integrity. I always keep the original (in its own file) and compare. I learned some good stuff though here.- https://customersuccess.autodesk.com/course?id=486 Creating Surfaces from Point Cloud Data in Civil 3D - https://customersuccess.autodesk.com/course?id=487 How to Manage Large Surfaces Efficiently

[TerryDotson]

I've received projects before and naturally dumped them into a folder of my own choosing and had this happen.  Sadly the path does not appear to allow storing a relative path, which would seem to be the best initial approach.  With that, folder dumps wouldn't matter, if it was in the same location relative to the drawing file, it would find it.  So if that's not on the wish-list it should be.  You would have thought being an app based on AutoCAD which pioneered relative paths (in xrefs and images) that would have been an option.

So in this case you knew where the DEM lived now.  If this were being automated in a Surface Path Audit tool, it would seem logical to first search the drawing path and all subfolders, if found make that change automatically (since it was in a subfolder)?   Then if not found I suppose the automation could begin searching all available drives (much slower) for the DEM file.  At this point you run into the real possibility that a found file name might not necessarily be the right file, so prompting for "Use D:\FOLDER\FILENAME.TIF <Y>/N:" would be best.  Just pondering the most appropriate way to make this easier and quicker when opening a drawing and getting a "Referenced file not found error".

I added the relative path item to the wish list if anyone wants to vote it up.

[asankaHW]

Hi Jeff,

I worked on a different project today and i came across an interesting outcome. Attached are the files and this is what i did.

1. Created a surface using the TIFF file shown below and the file size ended up at 51MB
2. Then i exploded that surfaces down to 3D polylines and add them as contours to create the TEST1 file, and you can see the file size doubled. Do you know why this happens?

[asankaHW]

And my TEST file

[jefflambert9091]

It's all about vertices. Look in your stats in the surface and compare how many points there are. I try not to explode and C3D objects. That's what the extract objects is for. Then the mapclean. I have experimented with every way possible with dem files, lidar and gis contours. I can Sent you my analysis sheets. With a dem it's best to do what I said before. Start a new surface and add the dem in the edits. If you want to get away from the file then extract the contours and mapclean.

[jefflambert9091]

Send not sent. Sorry for the typos. Been using my phone. 

[asankaHW]

Hi Jeff,
I'd love to see your stat file. Also, I'm a bit lost on how following the instructions. Are you able to email me like a very basic PowerPoint or screen shots of step by step instruction on the info you mentioned above? I hope I'm not asking for much. Either way I appreciate your input. My email is asanka@haighworkman.co.nz
Thank you.