Large Terrain Mesh

dbwv69

Can you post your model. It will probably not fit the 3d ware house limit and probably not the Google docs but possibly one of the free ftp sites or post a section. Thinking you may not have not spent enough time with MeshLab? Check drop box it gives a large file size upload

Unfortunately, I don't really have a model yet, at least not one of the full area involved. Originally, I tried creating one and it killed Sketchup so I was forced to seek out alternatives that could simplify the poly counts of the terrain mesh while maintaining an acceptable level of detail. Ultimately, I decided to split the terrain mesh into several segments but again, each of them alone is more than Sketchup can handle without significant poly reduction.

I have managed to make some progress using Mesh lab, after considerable efforts were made to determine why the program kept crashing. As it turns out, it was the file format (Collada) that I had been using to get the data into Mesh Lab. I switched to using OBJ files and the program appears to be much more stable now.

For example, using Mesh Lab I was able to take a terrain mesh containing 400,000 faces and reduce it down to a mere 10,000 faces while mataining a relatively nice appearance. Granted, that was an overall poly reduction, which doesen't exactly achieve my goal of maintaining high levels of detail in the valleys and low levels of detail in the mountains, but it is closer than any previous methods I have tried.

By dividing the mesh, using poly reduction, and careful trimming of unnecessary areas, I am now convinced that I will eventually be able to create a nice terrain mesh for use with the model(s) I am planning. It is only a matter of time now.

bjornkn

I have no idea what makes you think that I will get any bucks by advicing you to buy a plugin?
I make no plugins or programs currently, and I will not receive any royalties or any other "bucks" by pointing at any non-free plugins.

I don't use Meshlab (free?) or Global Mapper ($350+?), but have bought Amorph and Artisan, and am very happy that I did because it saves me tons of time and makes it possible to do things in SU that would be impossible without them. BTW I have also bought that Mootools/Polygon Cruncher as well as Okinos NuGraf/Polytrans (which will also poly-reduce) and many other tools.
When I need to screw a screw into a wall I prefer to buy a (cheap) screwdriver instead of trying to use a hammer, or to spend hours/days looking for a free screwdriver or make one myself.
BTW, I just did a little test on that handmade terrain I posted earlier. By downsampling selected areas with Amorph (10secs) it looks identical at a distance, and is now 4000 faces, and with the ortho photo intact. Even at <2000 faces it looks pretty good. As you're not interested in solutions that costs a few bucks I won't bother to post the results though.

But, by all means, it would be great if you could write a free polygon reducer plugin that makes it possible to do local/area(/altitude?) reductions, and will allow you to stitch the parts together easily afterwards. I'm sure you could even charge a few bucks for such a plugin - and I would probably buy it too

dbwv69

I had no idea if you were the one who made the plugin or not but after your having mentioned it several times, even after I made it clear that I wanted to seek free alternatives, it certainly began to look like you either had an agenda or were affiliated in some way.

As for using hammers and screwdrivers...

My problem is somewhat unique and as a direct result, it requires creative and innovative solutions. Fortunately, there are no deadlines so I can spend as much time as I like while trying to find an adequate solution.

How do you think that all these nifty plugins and addons for Sketchup were created in the first place? Quite simply, because someone took the time to do the hard work while trying to find a solution to a problem, whatever that problem might have been. Besides, some of us simply like the challenge.

Speaking of test results, using Meshlab and a variety of other tools, as mentioned earlier I was able to take a terrain mesh containing over 400,000 faces and reduce it down to a mere 10,000 faces while still being able to maintain an appearance that was very close to what I am seeking. All without the need to purchase anything. Plugins are great but they can't "fix" everything.

We aren't talking about a small flat patch of land around a house or even a small sub-division here. I am planning to model an area of over 25 square miles in mountainous terrain and knew very well that it would not be easy before I even began the project. Sure, I could have simply used CAD or one of the other miriad of paid-products made specifically for a project such as mine, but what fun would that have been?

Sometimes it isn't about the destination but about the journey itself.

@bjornkn said:

I have no idea what makes you think that I will get any bucks by advicing you to buy a plugin?
I make no plugins or programs currently, and I will not receive any royalties or any other "bucks" by pointing at any non-free plugins.

I don't use Meshlab (free?) or Global Mapper ($350+?), but have bought Amorph and Artisan, and am very happy that I did because it saves me tons of time and makes it possible to do things in SU that would be impossible without them. BTW I have also bought that Mootools/Polygon Cruncher as well as Okinos NuGraf/Polytrans (which will also poly-reduce) and many other tools.
When I need to screw a screw into a wall I prefer to buy a (cheap) screwdriver instead of trying to use a hammer, or to spend hours/days looking for a free screwdriver or make one myself.
BTW, I just did a little test on that handmade terrain I posted earlier. By downsampling selected areas with Amorph (10secs) it looks identical at a distance, and is now 4000 faces, and with the ortho photo intact. Even at <2000 faces it looks pretty good. As you're not interested in solutions that costs a few bucks I won't bother to post the results though.

But, by all means, it would be great if you could write a free polygon reducer plugin that makes it possible to do local/area(/altitude?) reductions, and will allow you to stitch the parts together easily afterwards. I'm sure you could even charge a few bucks for such a plugin - and I would probably buy it too

bjornkn

@dbwv69 said:

I had no idea if you were the one who made the plugin or not but after your having mentioned it several times, even after I made it clear that I wanted to seek free alternatives, it certainly began to look like you either had an agenda or were affiliated in some way.
My agenda is just to use the right tool for the job.
@unknownuser said:

My problem is somewhat unique and as a direct result, it requires creative and innovative solutions. Fortunately, there are no deadlines so I can spend as much time as I like while trying to find an adequate solution.

Not more unique than that we all have to face it all the time when making models in SU, and particularly terrains.

@unknownuser said:

How do you think that all these nifty plugins and addons for Sketchup were created in the first place? Quite simply, because someone took the time to do the hard work while trying to find a solution to a problem, whatever that problem might have been. Besides, some of us simply like the challenge.

Exactly! And some of those great plugin makers wants to make a living from their hard work, while others do it just for fun/challenge.

@unknownuser said:

Speaking of test results, using Meshlab and a variety of other tools, as mentioned earlier I was able to take a terrain mesh containing over 400,000 faces and reduce it down to a mere 10,000 faces while still being able to maintain an appearance that was very close to what I am seeking. All without the need to purchase anything. Plugins are great but they can't "fix" everything.
But then you already have the solution then? Your 25 sq miles should be around 5-6 million triangles at 3x3m resolution, which should convert to around 150k faces in SU, which might work. Then you just have to figure out how to texture it with a 70+ Mpx orthophoto to get 1x1m resolution (which isn't much btw)...

@unknownuser said:

We aren't talking about a small flat patch of land around a house or even a small sub-division here. I am planning to model an area of over 25 square miles in mountainous terrain and knew very well that it would not be easy before I even began the project. Sure, I could have simply used CAD or one of the other miriad of paid-products made specifically for a project such as mine, but what fun would that have been?

Sometimes it isn't about the destination but about the journey itself.

OK. As you don't seem to be interested in advice along that road (if it costs anything at all) I think I'll stop spending my time on this "journey" of yours.
Looking forward to see the results though.

dbwv69

@bjornkn said:

But then you already have the solution then? Your 25 sq miles should be around 5-6 million triangles at 3x3m resolution, which should convert to around 150k faces in SU, which might work. Then you just have to figure out how to texture it with a 70+ Mpx orthophoto to get 1x1m resolution (which isn't much btw)...

Texturing with the orthophoto no longer a concern to me because I have already solved that problem and it's resolution isn't critical because it will only be used as a background texture on the mountains.

@unknownuser said:

OK. As you don't seem to be interested in advice along that road (if it costs anything at all) I think I'll stop spending my time on this "journey" of yours.
Looking forward to see the results though.

That's probably a good idea because debating "free" v/s "paid" isn't doing a thing to help me achieve my goal. BTW: Did I detect a note of sarcasm there?

mac1

dbwv69
I have had some what similar problem with Su=>Collada=>MeshLab=< Su( Collada) and then see a number of self intersecting faces and the obj works much better. Belnder has bug reports, ref. Collada import, my check of latest stable release shows the patch is not yet included but fix is known.
Ploy reduction is one of the easier filters in MeshLab to apply ,but as I am sure you know there are many more. I was thinking the Poisson smoothing could help your problem. I dabble with MeshLab so if you can post even a section I'll take a look. May not get any where but will at least try.
G day and good luck

charly2008

Hello Geo specialists,

I am a beginner in terms of geographic information systems. But I am very interested in this subject.
I have a question and would be delighted to receive a response from you. Is it possible to produce a TIN from SRTM 90m Digital Elevation Data and how is it done?. I own Global Mapper 11. Thanks in Advance.

Charly

dbwv69

@mac1 said:

dbwv69
I have had some what similar problem with Su=>Collada=>MeshLab=< Su( Collada) and then see a number of self intersecting faces and the obj works much better. Belnder has bug reports, ref. Collada import, my check of latest stable release shows the patch is not yet included but fix is known.
Ploy reduction is one of the easier filters in MeshLab to apply ,but as I am sure you know there are many more. I was thinking the Poisson smoothing could help your problem. I dabble with MeshLab so if you can post even a section I'll take a look. May not get any where but will at least try.
G day and good luck

Thanks for the help, I appreciate it.

I was reading about the Poisson smoothing and while I have not yet experimented with it, the reports I read do sound promising. So far, using MeshLab I have been able to achieve decent results by applying a Quadric Edge Collapse Decimation filter, which produced a TIN that closely resembled the original symmetrical mesh, only at a greatly reduced polygon count.

However, I did notice one thing that could potentially cause problems with proper alignment of the completed terrain meshes. The mesh somehow gets rotated on it's axis when it's imported back into Sketchup. I don't know if it's caused by MeshLab or some part of the convoluted import/export process needed between the various programs.

I extracted a small sample of the area I am working with from the original 3 meter Lidar data, and exported that to a DXF 3D mesh file at full resolution. I can convert it to other formats if needed. See attachment: Sample Section DXF.zip

Sample Section DXF.zip

dbwv69

@charly2008 said:

Hello Geo specialists,

I am a beginner in terms of geographic information systems. But I am very interested in this subject.
I have a question and would be delighted to receive a response from you. Is it possible to produce a TIN from SRTM 90m Digital Elevation Data and how is it done?. I own Global Mapper 11. Thanks in Advance.

Charly

For the best results, using Global Mapper, you can export the data to either a DXF Mesh file or a DXF 3D Face file but you will need Sketchup Professional to import it.

Alternatively, using Global Mapper, you can export the elevation data to a DEM (Digital Elevation Model) and import that into the free version of Sketchup but the results (in my opinion) aren't as good.

Another method is, using Global Mapper, export the elevation data to an XYZ file and import that into Sketchup as a point cloud with the Cloud plugin. You will then have to triangulate it with either the Cloud plugin or another plugin designed for that purpose.

Lastly, using Global Mapper, you can generate contour lines and export them as Vector data to a DXF file and import that into Sketchup then convert the contours to a mesh using the Sandbox tools but again, you will need Sketchup Professional to import the DXF file.

Whichever method you choose, it is still possible to have problems with the amount of data involved, depending on the size of the area you are using. If you have problems, try changing the sample spacing to a higher number in Global Mapper, prior to export. It will reduce the amount of data but the resolution will suffer as a result.

mac1

Thanks for the file, I have SU7 free with the dxf import add on so was able to open file, used TIGS obj exporter to create obj file for MeshLab. In my dabbling https://sites.google.com/site/sagesuwiki/tutorials/tips#TOC-MeshLab:-Centric-View-of-Polygon-Me I have convinced my self the export by kmz is better than dae alone and that I seem to run into problems with dae and MeshLab declaring self intersecting faces. I have also noted the axis issue and scaling but previous apps I did not worry too much because of the relative small components I was dealing with.
For your case in MeshLab ( obj file) there was 479K+ duplicate vertices deleted. ( I don't merge vertices because the model can get distorted. For terrain probably Ok but not component model. Zero self intersecting faces, zero non manifold vertices and edges I could see (ML paints them red so for large mesh they get hard to see). Did quad collapse decimation and at Ml recommended value collapsed down to 49k+ vertices and 98k+ faces. Will dabble some more but for what it is worth here is the dxf file exported from MeshLab fileBaseline ML.zip

charly2008

Hi dbwv69,

Thank you very much for your detailed explanation. I will try the options described.

Charly

bjornkn

@dbwv69 said:

That's probably a good idea because debating "free" v/s "paid" isn't doing a thing to help me achieve my goal. BTW: Did I detect a note of sarcasm there?
I'm afraid I couldn't hide it completely
Nevertheless I couldn't resist wasting another hour+ on this terrain after you posted that "little" dxf detail.
All free tools (I think there are free guide point tools? Although I did use the one in Amorph)
I will not post the Amorph version... It didn't have a chance trying to polyreduce that beast of a terrain in any reasonable amount of time, but could easily build a terrain on top of the dxf.

solo

Hey guys, I have not read this whole thread, I just jumped in here, I'm guessing it's about using large terrains, if not please ignore everything from here.

I say do not do it, SU buckles at it's knees, use a third party app like Terragen or Geo control, even the new Vue can do it great these days.

If you do need to the use a good reducing app like deep exploration (very expensive).

Here is your sample, brought directly into SU was 35MB, reduced to 2.6MB, can go lower but this was a good balance as nothing much in detail was lost, I reduced it by 90%.

sample section reduced by 90 percent.jpg

Softened:

sample section red1a.jpg

dbwv69

Very good work! The results you achieved are exactly what I am looking for. How did you do it?

@solo said:

Hey guys, I have not read this whole thread, I just jumped in here, I'm guessing it's about using large terrains, if not please ignore everything from here.

I say do not do it, SU buckles at it's knees, use a third party app like Terragen or Geo control, even the new Vue can do it great these days.

If you do need to the use a good reducing app like deep exploration (very expensive).

Here is your sample, brought directly into SU was 35MB, reduced to 2.6MB, can go lower but this was a good balance as nothing much in detail was lost, I reduced it by 90%.

[attachment=1:20afzex3]sample section reduced by 90 percent.jpg[/attachment:20afzex3]

Softened:

dbwv69

I obtained similar results using the method mentioned earlier. The face counts are still high but it is definitely a step in the right direction. I'm thinking I can get a reduction of around 90% and still maintain just enough detail in the valleys to make it useable.

It may take some tweaking to get it just right but I am more convinced than ever that it can be achieved.

@mac1 said:

Thanks for the file, I have SU7 free with the dxf import add on so was able to open file, used TIGS obj exporter to create obj file for MeshLab. In my dabbling https://sites.google.com/site/sagesuwiki/tutorials/tips#TOC-MeshLab:-Centric-View-of-Polygon-Me I have convinced my self the export by kmz is better than dae alone and that I seem to run into problems with dae and MeshLab declaring self intersecting faces. I have also noted the axis issue and scaling but previous apps I did not worry too much because of the relative small components I was dealing with.
For your case in MeshLab ( obj file) there was 479K+ duplicate vertices deleted. ( I don't merge vertices because the model can get distorted. For terrain probably Ok but not component model. Zero self intersecting faces, zero non manifold vertices and edges I could see (ML paints them red so for large mesh they get hard to see). Did quad collapse decimation and at Ml recommended value collapsed down to 49k+ vertices and 98k+ faces. Will dabble some more but for what it is worth here is the dxf file exported from MeshLab file[attachment=0:24kp526k]Baseline ML.zip[/attachment:24kp526k]

dbwv69

The first example (hand sketch) you posted reminds me of an idea that I had originally considered, where I thought about "tracing" over the grouped contour lines to capture all the major details (shape) of the mountains. After some brief experimentation, I quickly discovered that it would have taken forever to do because I wish to maintain as much detail as possible in the lower elevations and especially in the stream beds. It is still an interesting notion, however.

@bjornkn said:

@dbwv69 said:

That's probably a good idea because debating "free" v/s "paid" isn't doing a thing to help me achieve my goal. BTW: Did I detect a note of sarcasm there?
I'm afraid I couldn't hide it completely
Nevertheless I couldn't resist wasting another hour+ on this terrain after you posted that "little" dxf detail.
All free tools (I think there are free guide point tools? Although I did use the one in Amorph)
I will not post the Amorph version... It didn't have a chance trying to polyreduce that beast of a terrain in any reasonable amount of time, but could easily build a terrain on top of the dxf.
[attachment=0:2qr61cuc]dxfterrs.jpg[/attachment:2qr61cuc]

dbwv69

This is slightly off topic but I just had to say that I had a look at your website... NICE WORK!

@solo said:

Hey guys, I have not read this whole thread, I just jumped in here, I'm guessing it's about using large terrains, if not please ignore everything from here.

bjornkn

@dbwv69 said:

The first example (hand sketch) you posted reminds me of an idea that I had originally considered, where I thought about "tracing" over the grouped contour lines to capture all the major details (shape) of the mountains. After some brief experimentation, I quickly discovered that it would have taken forever to do because I wish to maintain as much detail as possible in the lower elevations and especially in the stream beds. It is still an interesting notion, however.

The amount of detail is entirely up to you, with full control, and would not take forever. Took about 10-15 min to place ~1400 guide points on the rightmost terrain.
I think you get a bit blinded by the massive amount of data in the mesh, and think that it must be precisely like that in real life. But in reality it shows a smoothed version (3x3m) of the terrain that looks like it's covered in fine sand or snow when you get close - no crisp details. It's like a heavily blurred photo. A real terrain doesn't look like that at all in the details.
Here's a "stream" in a flat terrain, 15m wide and 3m deep with vertical sides - 15 faces.
On the right side is a "gridded" version with 3x3m resolution (using Terrain Reshaper - free) and ~8000 faces!
Doesn't look much like the "real" terrain, even though it has "much more detail"?

Do you have a photo of the area? Ground level? The shapes indicates that there must be lots of boulders, rocks, gravel everywhere?
Where is it?

BTW, Solo wrote that he used Deep Exploration, which costs $400-$700 per year
Nice program though. I have an older version of the CAD/expensive version, bought when it was much cheaper and with no annual fees. No skp, Collada, FBX though.

bjornkn

Thanks for the coordinates.
After having a look I'm even more confused why you insist on having all the details in the mountains, with ridge lines etc, when they are not visible at all because of all the trees?
The perceived landscape is even much smoother in the hilly areas than on my simplified versions. Not only will a more detailed version contain way too many faces, but it will also look wrong because you should really "model" the forests instead of the ground below, as it isn't visible anyway.
And at the same time you have the ground level with Lidar clutter, too little details and too smoothed. I think you'd be much better off with making this by hand. That way you may even end up with a full model that is managable in SU

dbwv69

@bjornkn said:

Thanks for the coordinates.
After having a look I'm even more confused why you insist on having all the details in the mountains, with ridge lines etc, when they are not visible at all because of all the trees?
The perceived landscape is even much smoother in the hilly areas than on my simplified versions. Not only will a more detailed version contain way too many faces, but it will also look wrong because you should really "model" the forests instead of the ground below, as it isn't visible anyway.
And at the same time you have the ground level with Lidar clutter, too little details and too smoothed. I think you'd be much better off with making this by hand. That way you may even end up with a full model that is managable in SU

While the primary purpose of the terrain will be to display various scenes from the area, it will also be used to show mining and other activity which requires that some level of detail remain in tact. The mountains do not have to have much detail, other than the general shape, but the lower elevations absolutely must have crisp boundaries because of the proximity of homes, roads, streams, and railroad lines, all tightly packed in among the mountains. You would have to see the area up close to understand fully because satellite images just don't do it justice.

Drawing an area of this size by hand is not a task that I would want to even contemplate doing. Especially with the terrain involved.