topic Re: Can't explode large terrain mesh. in AutoCAD Forum

Can't explode large terrain mesh.

Loofer — Thu, 19 Feb 2015 10:59:08 GMT

I have to bring a large (300Mb) 50m grid, terrain mesh into 3DS Max, usually it won't let me import directly so I open the dxf in Autocad and explode it first. It's usually slow but this time it's just not playing ball at all, last night I left it sitting for over 4 hours after hitting explode with no luck.

Can I split the mesh into smaller blocks first or is there any better way to explode large entities like this?

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 11:25:37 GMT

Hi,

if a max-file has 300MB you will not have big chances to work with AutoCAD on that model at all.

What do you want to do with that terrrain data? Maybe when we know what your goal is we can find workarounds.

- alfred -

Re: Can't explode large terrain mesh.

Loofer — Thu, 19 Feb 2015 11:57:34 GMT

Hi Alfred, I'm an architectural CGI artist and I produce photomontages for planning applications. In order to position my cameras in Max and validate their accuracy I buy a terrain tile from OSNI in the form of a dxf mesh and import it into 3DS Max. I can then render this out and overlay it onto a site photograph so that it matches the real horizon to prove the camera position is accurate.

Problem is, It has to be a large tile because it has to stretch to the visible horizon.

As I say, I've had problems trying to bring the original mesh straight into Max and have found that exploding it first then importing works better but occasionally I get a mesh that just locks everything up.

I've saved the 300Mb dxf as a dwg and the size comes doen to 66Mb but it still hangs. I was trying to think of a way of maybe breaking the mesh up into qurters and exploding each indivitually but AutoCad isn't my strong point and I hit a wall.

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 12:08:42 GMT

Hi,

am I understandig that correct that you need the terrain modell in 3DS-Max ... but you can't get the data into 3DS-Max ... and so you tried to pass the dxf-data through AutoCAD just to split it into tiles?

>> I buy a terrain tile from OSNI in the form of a dxf mesh

What other data-formats does this company provide? Maybe any other format than DXF is the better format to be imported into/used by 3DS-Max without doing some workarounds. If you show the link to the data we can look (and if it's free to download, we can try) what way may work.

Interestingly my first thought was that 3DS-Max will have less problems with the data amount than AutoCAD, so I'm wondering now that you need AutoCAD to prepare the data for 3DS-Max 😉

- alfred -

Re: Can't explode large terrain mesh.

Loofer — Thu, 19 Feb 2015 12:45:28 GMT

Yes, that's my workflow. I actually skipped a step in explaining things, OSNI is the Ordnance Survey office for Northern Ireland, they sell terrain data in numerical tables (XYZ co ordinates on 10m or 50 grids) these are then brought into Global mapper and turned into meshes and exported as DXF's. Sometimes I do this myself, often the client provides the meshes as is the case here. Unfortunately the only formats that Globalmapper and Max share are DXF and DWG niether of which are working for me.

[EDIT] I can stick this in a dropbox folder if you would like to look at it but there's no obligation.

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 12:48:04 GMT

Hi,

>> I can stick this in a dropbox folder

Let's try that.

Maybe I have some ideas when having access to the model.

- alfred -

Re: Can't explode large terrain mesh.

Loofer — Thu, 19 Feb 2015 13:03:57 GMT

Great, thanks Alfred, I've put the smaller dwg in the folder below.

Let me know if you need anything else.

https://www.dropbox.com/s/0gelgxiji76oe0e/Terrain%20with%20GPS.dwg?dl=0https://www.dropbox.com/s/0gelgxiji76oe0e/Terrain%20with%20GPS.dwg?dl=0

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 14:08:00 GMT

Hi,

while my system is running hot ... 😉

...do you have a link that describes what type of data (formats of data) is available from the provider?

- alfred -

Re: Can't explode large terrain mesh.

Loofer — Thu, 19 Feb 2015 14:17:14 GMT

Alfred

Here's the site where you can purchase the tiles of data.

https://mapshop.nidirect.gov.uk/Catalogue/Digital-products/Height-products

There is only one way to purchase though and that's as a text file. You get an X and Y map co ordinate with the associated Z or hieght data for each point over a 10m or 50m grid, then a mapping package translates that into a mesh. I only have access to global mapper and that can only create DWG or DXF files, nothing else is compatable with Max.

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 14:19:42 GMT

Hi,

>> that's as a text file

Do you have Civil 3D available?

- alfred -

Re: Can't explode large terrain mesh.

Loofer — Thu, 19 Feb 2015 14:28:52 GMT

I don't but my client has, do you think it would help?

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 14:40:01 GMT

Hi,

>> I don't but my client has, do you think it would help?

I guess yes, it depends now on the exact format of the TXT file.

The idea is to create a surface from the points in Civil 3D, then (after maybe surface-simplification) you can export the model as LandXML or just the contours of the surface (depending on how exact you need the geometry).

The DWG file itself can't be used at daily work, to slow to load and to slow to work with. That is what I think after "playing" with that sample for some minutes.

- alfred -

Re: Can't explode large terrain mesh.

Loofer — Thu, 19 Feb 2015 14:53:56 GMT

OK I'll get onto them and give it a go, at least I know it's not just my machine being decrepid.

Another though just occured to me, I may be able to split the text file into 4 and see if I can generate smaller meshes that way....

Thanks very much for your efforts, much appreciated, I'll let you know if we get anywhere.

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 15:02:23 GMT

Hi,

if you can upload a txt file, I can try the workflow using Civil 3D ==> LandXML ==> 3DS Max.

- alfred -

Re: Can't explode large terrain mesh.

Loofer — Thu, 19 Feb 2015 16:01:03 GMT

Loading the terrain in strips seems to be working for me but I've uploaded the files in case you want to try out of curiosity. The client must have purchased this terrain from a different source as they are .asc files not .txt.

https://www.dropbox.com/s/siovub3rqsebd32/DTM.zip?dl=0https://www.dropbox.com/s/siovub3rqsebd32/DTM.zip?dl=0

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 20:54:34 GMT

Hi,

the fastest way I found now:

use Civil 3D to import the ASC-files and create surfaces for each of the ASC-files.
create a new surface and import all the previous ones into this.
if necessary create a boundary for the area you need, if you can limit it.
export the new surface to a DEM with the raster-distance you like/you need for your workflow.
create a new drawing in Civil 3D and import that DEM (that creates a surface again, but less complex)
make sure a surface style is set to display trianges
save that drawing
start 3DS-Max and import this drawing.

I tried that with the complete model + a 250m raster distance for the temporary DEM ... the results are:

about 15min work (depending on speed of workstation, of course!
at least the max-file has 15MB in that case and can be handled quite well in 3DS-Max.

HTH, - alfred -

Re: Can't explode large terrain mesh.

Alfred.NESWADBA — Thu, 19 Feb 2015 21:39:55 GMT

Hi,

one additional info: the fastest way to get some visualisation based on your ASC-files (within 2 minutes) would be >>>Autodesk InfraWorks<<<.

- alfred -

Re: Can't explode large terrain mesh.

Loofer — Fri, 20 Feb 2015 10:21:29 GMT

Excellent work Alfred, thanks very much . I'm going to see if I can grab a copy of Civil AutoCad and try this out for future meshes, sounds faster than my current workflow.

Thanks again.