Large Terrain Mesh
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Yes, simplifying contour curves is a must, at least with the ones we get here in Norway from SOSI!
You have a lot of useful tools ThomThom
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When finished, the terrain will primarily be used to show individual scenes as well as video along the entire length of the historic rail line from a ground level perspective. Imagine sitting in the cab of a locomotive as it travels. That is the perspective I am seeking.
Ideally, everything at ground level, streams, roads,etc... would be at maximum resolution and everything upwards (mountains) would be at a considerably reduced resolution to maximize performance.
So far, the best results I have managed to obtain, which satisfied both requirements of detail and performance, were achived by exporting the raw DEM data to an XYZ point cloud file then importing that into Sketchup and triangulating it there. The mesh was more detailed and much cleaner than anything generated using other methods with the added benefit of being able to trim or fine tune the point cloud prior to triangulation.
Currently, I am experimenting with dividing the area into 3-5 quadrants or irregular sections with some overlapping terrain between each to permit the generation of a seemingly continuous video by carefully synchronizing camera points on a given path.
However, due to the irregular borders of each terrain, I am having difficulty with precisely matching each terrain in 3-D space after import and conversion so that camera paths, roads, etc.. will line up. Additionally, it is important for the terrains to match because I need to overlay topo imagry for building location points and eventually for aerial imagry projection.
In my previous experimentation with generating contours from the raw elevation data, the results were somewhat less than satisfactory. Regardless of what I tried, detail was always lost at the ground level, even when I used contours at 1 meter spacing. Otherwise, I agree that simplifying contour curves is a must.
The Amorph and Artisan plugins look great but I prefer to keep it "free", at least for now anyway.
@bjornkn said:
First of all you need to decide what level of detail you need, and where you want it.
If you're going down at ground level you need more detail, but you'll probably not getting that close to the entire terrain?{SNIP}
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@bjornkn said:
Yes, simplifying contour curves is a must, at least with the ones we get here in Norway from SOSI!
Aye! I often wish I worked on project located in Denmark or similar places.
(Hvor i landet holder du til?)
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Out of curiosity I generated an XYZ file at my preferred resolution of 300% above normal sampling and it contains 395983 points. I wonder how long it would take to triangulate and how many triangles the resulting mesh would contain. I have no idea actually, but I am thinking days to triangulate on a P4 and millions of points. Am I even close? For that matter, could Sketchup handle a terrain mesh of that size, especially after it was populated with "stuff"?
Oh how I wish I could use a simgle terrain mesh because multiple terrain meshes are going to be a real pain. LOL
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That's definitely going to be a pain in the butt to handle in SU. Best would (probably) be to somehow create the footprints of the buildings and everything else and work on those pieces separately.
Speaking of old trains; this is where I was on Saturday:
It goes all along a national park and wild reserve (a flood area of the river Danube)
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Nice train! It reminds me of one near my home called Cass Scenic Railroad. It was an old logging railroad years ago and was converted into a scenic park for tourists.
On another note, it looks like the decision has been made for me. I tried importing the full XYZ file into Sketchup and it did not like it at all. I imagine that triangulation would crash it for sure.
So, it looks like I will be splitting the area up into separate meshes afterall. Dividing it up into 5 separate meshes would yeild areas with about 75-80 thousand points each. I am not certain but I think even that might be pushing the limits a bit.
That also leaves the question of how to line up the meshes. This is not going to be easy. LOL
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I did some further testing to see if I could increase the sample spacing, thus reducing the point counts and resulting triangles contained in the generated terrain mesh while still managing to achieve an acceptable result.
First, I created 5 different XYZ files, each having different sample spacings ranging from 100 to 500 percent, from a test area of approximately 1 square mile.
XYZ Sample Spacing = Points
100% = 193053
200% = 48336
300% = 21518
400% = 12008
500% = 7696Next I generated terrain meshes from the imported point clouds for the 400 and 500 percent sample spacing XYZ files. I already knew that the 300 percent file would have yeilded too many triangles in the resulting terrain mesh so it and the others were not tested.
Triangulation Samples:
12008 Points = 23556 Triangles (Faces)
12008 Points = 35563 Edges7696 Points = 12513 Triangles (Faces)
7696 Points = 19972 EdgesThe 500 percent file yeilded a terrain mesh that was just beyond what I would consider an acceptable result but the 400 percent file yeilded a terrain mesh which appeared to be useable.
Using crude math, I estimate that the XYZ file for the entire area would contain about 180,000 points and if divided up into 5 distinct areas, each would contain about 36,000 points. The number of triangles that would be contained in each resulting terrain mesh is unknown.
While waiting for the test meshes to triangulate, an idea came to me...
I could generate and import a point file for the entire area, then edit or delete the points, thus shaping them into 5 distinct areas. It would solve the problem of keeping each mesh in the same 3-D space.
However, I remain uncertain of how I would be able to also import topo or satellite imagery and keep it properly aligned with each terrain mesh. I suppose I could create a point file for a square area as opposed to an irregular area, then trim the point cloud down after everything is aligned but that would mean a lot of extra overhead. There is also the problem of trimming the projected texture images down while keeping them properly aligned.
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Also using crude math, that would give you a resolution of 18mx18m each square.
Or 14x14m with 400% and 12008. That is much more than you need in remote, less visible areas, but way too little precision for close-up areas as far as I can tell..
I don't know if this is a paid job or not, but if it is I think you're wasting a lot of time trying to save a few bucks. I can't see how you could possibly make such a large area at an acceptable resolution from a triangulated point cloud. You obviously have access to the full data and CAD software since you can export contour lines and/or point clouds?
With a TIN you can also easily align a topo orthophoto, because it is actually possible to see the terrain from above. It would also be very easy to make the terrain rectangular. And with Amorph you could output point clouds for the detail areas only and generate accurate meshes that passes through every one of those points. Great for building sites etc too.
How are you going to handle vegetation, buildings, poles, masts, people, cars(?), tracks + the train itself?
SU is not gonna like 300-500k faces + all the props and objects I'm afraid.
Are you going to render this inside SU, or in some external program?@thomthom: I'm in Kristiansand (just updated my profile too )
Just as unflat here as in Trondheim
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Unfortunately, this isn't a paid project. It is part of a much larger ongoing personal research project I am conducting. Think of it as a means to visualize the things I discover.
As for saving a few bucks, I'm not trying to be stingy, not by any means. It's simply a matter of money. In these tough economic times, I am sure you can understand. Ordinarily, I would not hesitate to spend whatever is necessary in order to achieve my goal but in this case, I am forced to seek alternative and sometimes even creative solutions. It is by no means easy but I like the challenge.
I completely agree about what I have come to call "dual resolution" and have been seeking that very thing, without much success I am afraid. If there were an easy way to keep high resolution at the lower elevations while greatly reducing the resolution at the higher elevations, I would love to do exactly that.
You are correct about my having direct access to high resolution data but Sketchup is the only CAD-like application I am using. I use Global Mapper GIS software to export the raw data into a variety of forms including DEM, DXF, contours, etc... then import that into Sketchup.
The data itself is 3 meter resolution Lidar data provided by the USGS and is nothing short of beautiful when rendered at maximum resolution but it is far more than Sketchup can handle so I am doing my best to find a decent compromise.
My original approach was to use a TIN generated by importing the DEM directly into Sketchup with an accompanying topo overlay projected as a texture. This worked great until I tried to scale things up.
Here is a sample image of a small terrain mesh generated by importing a high resolution DXF mesh file into Sketchup. As you can see, the resolution is superb, but working with the mesh alone was just about all Sketchup could handle.
@bjornkn said:
Also using crude math, that would give you a resolution of 18mx18m each square.
Or 14x14m with 400% and 12008. That is much more than you need in remote, less visible areas, but way too little precision for close-up areas as far as I can tell..
I don't know if this is a paid job or not, but if it is I think you're wasting a lot of time trying to save a few bucks. I can't see how you could possibly make such a large area at an acceptable resolution from a triangulated point cloud. You obviously have access to the full data and CAD software since you can export contour lines and/or point clouds?
With a TIN you can also easily align a topo orthophoto, because it is actually possible to see the terrain from above. It would also be very easy to make the terrain rectangular. And with Amorph you could output point clouds for the detail areas only and generate accurate meshes that passes through every one of those points. Great for building sites etc too.
How are you going to handle vegetation, buildings, poles, masts, people, cars(?), tracks + the train itself?
SU is not gonna like 300-500k faces + all the props and objects I'm afraid.
Are you going to render this inside SU, or in some external program?@thomthom: I'm in Kristiansand (just updated my profile too )
Just as unflat here as in Trondheim -
I'm officially abandoning point clouds.
I can't believe I didn't see it before but Global Mapper gives me the ability to export DXF mesh files, as mentioned previously. As it turns out, I can also change the resolution of the exported mesh files on the X and Y axis to make the exported DXF mesh file more Sketchup friendly.
It doesn't solve the "dual resolution" problem but it yeilds the same or better results than the point clouds did, and all without the hassle of converting DEM's to XYZ files then importing them as point clouds and waiting for triangulation to finish. Overall, the process is 100x faster.
I'll be the first to admit that I am by no means a Sketchup expert, especially where terrain meshes are concerned, but I am learning fast, the hard way.
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While reading over everything again, I just realized that we may have been using a term in very different contexts and with different meanings.
Several times I mentioned DEM's only in my case, I meant Digital Elevation Models (GIS data). From reading everything, it appears that the term DEM has a different meaning in Sketchup terms. Previously, I had always assumed that anything (terrain mesh) with a network of triangles was a TIN but it looks like I was mistaken. Can someone set me straight on this one?
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DEM and TIN are not SketchUp specific terms, but pretty general.
A DEM is a grid with evenly spaced x and y coordinates. For each intersection there is an altitude value. Which means than when viewed from above with no perspective any terrain will look exactly the same, just like a flat grid. It would be impossible to see if it was from the Alps or Holland. No roads, rivers or anything will be visible.
It uses the same grid everywhere, and wastes a lot of unnecessary vertices on flat or even large areas. Even flat water may use thousands of vertices.
A TIN, which means 'Triangulated Irregular Network' is different, because it only should place vertices where there needs to be one, like along a road for instance. Typically they are often made from contour lines stitched together.
The advantage is that you can see from above what the landscape looks like, where the roads are etc.
You can also get sharply defined roads etc, unlike with DEMs where everything is soft. A road in a DEM with a resolution of 6x6m will be pretty much invisible even when seen in perspective.
The main advantage of a TIN, particularly in SU, is that it can be made to cover a huge area at very little cost face-wise, because you can make it as coarse you like in distantly viewed areas, or as detailed as you like in ROIs that will be seen closeup.
Polygon reducers, like those present in Amorph and Artisan will be able to remove a lot of unnecessary faces in DEMs in areas of low frequency, like flat areas etc, but you will still not get crisp edges along roads etc. With orthophotos applied you will often get water climbing up on the terrain around lakes, rivers etc (just take a close look at lakes in Google Earth!) because the resolution is too coarse, and the waterline doesn't follow the square grid. With a TIN you will get a completely flat water plane which could be perfectly textured.
You can get good results with SU and the "From contours" tool in Sandbox, but be prepared to do lots of cleanup.
It isn't that bad actually. The technique I've used for years has been to draw coarse contour lines on top of the imported ones, adding points wherever there's a change of direction etc, and often skipping several altitudes. And then skin a selection of such contour lines with Sandbox, cleanup by flipping edges to remove flat areas, and then explode to merge with the rest of the topo.
The attached terrain was completely handmade using this technique. It took maybe 4 hours and is about 12000 faces?
I tried a small part of that terrain using the original contour lines, but simplified, and it ended up with 40000+ faces and wasn't looking any better. Today I would've used Amorph.
Attached also a version with orthophoto applied. As you can see the entire hill is covered with trees, so even that coarse topo was really overkill anyway. But today there very few trees left there - it's covered with houses, school etc. Unfortunately that job was canceled before I even got to start to build that school
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I am starting to believe that Sketchup simply doesn't have the horsepower to do what I need to do.
Does anyone know of any decent (free) 3D Mesh poly reduction programs? I heard that Blender can do it but I'll be darned if I can make heads or tales of it's odd user interface. I also tried Meshlab but it crashes at the drop of a hat.
Then there is the problem of converting DXF or other files to formats that the various 3D programs can import. You'd think the 3D software world was ran by monkeys with all the variations of files and interfaces that are out there.
This is starting to give me a headache the size of Texas.
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@dbwv69 said:
I am starting to believe that Sketchup simply doesn't have the horsepower to do what I need to do.
Does anyone know of any decent (free) 3D Mesh poly reduction programs? I heard that Blender can do it but I'll be darned if I can make heads or tales of it's odd user interface. I also tried Meshlab but it crashes at the drop of a hat.
Then there is the problem of converting DXF or other files to formats that the various 3D programs can import. You'd think the 3D software world was ran by monkeys with all the variations of files and interfaces that are out there.
This is starting to give me a headache the size of Texas.
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
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@dbwv69 said:
I am starting to believe that Sketchup simply doesn't have the horsepower to do what I need to do.
It's not so much lack of horsepower as getting used to driving with a manual shift
But if you want to drive at top gear everywhere you'll not gonna make it work for you.
If you absolutely need to have a 3x3m res in all of your terrain then SU is not the program for the job. 5-6 million polys can probably easily be handled with Blender, and so can most other non-free 3D programs, like LightWave, which is what I'm using when I need thousands of instanced 3D trees, rocks, grass and lots of polys.
In SU you have to "adapt to the terrain" and keep your polycount as low as possible wherever there's no need for lots of detail.
The SU community is so spoilt by all the great free plugins available, as well as lots of affordable ones. Sometimes you can't do without them, but sometimes you can spend a few days/weeks working hard instead of spending $39/$149.@unknownuser said:
Does anyone know of any decent (free) 3D Mesh poly reduction programs? I heard that Blender can do it but I'll be darned if I can make heads or tales of it's odd user interface. I also tried Meshlab but it crashes at the drop of a hat.
Then there is the problem of converting DXF or other files to formats that the various 3D programs can import. You'd think the 3D software world was ran by monkeys with all the variations of files and interfaces that are out there.
This is starting to give me a headache the size of Texas.
As advertised on this page currently there is http://www.mootools.com/plugins/us/sketchucation/index.htm which also comes with a poly reducer, the Polygon Cruncher. It works great, with lots of control, but again it is not free.
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@bjornkn said:
It's not so much lack of horsepower as getting used to driving with a manual shift
But if you want to drive at top gear everywhere you'll not gonna make it work for you.
If you absolutely need to have a 3x3m res in all of your terrain then SU is not the program for the job. 5-6 million polys can probably easily be handled with Blender, and so can most other non-free 3D programs, like LightWave, which is what I'm using when I need thousands of instanced 3D trees, rocks, grass and lots of polys.
In SU you have to "adapt to the terrain" and keep your polycount as low as possible wherever there's no need for lots of detail.
The SU community is so spoilt by all the great free plugins available, as well as lots of affordable ones. Sometimes you can't do without them, but sometimes you can spend a few days/weeks working hard instead of spending $39/$149.In my case, it was a matter of getting used to driving an automatic. I could achieve this with any number of other 3D programs, including AutoCAD, but none of them offer the simplicity or ease of use that Sketchup offers. For a model of this nature, the precision such as that offered by AutoCAD simply isn't necessary and would be akin to using a construction crew to build a park bench.
As stated previously, I do not need high resolution in the entire model and am trying to achchieve some level of compromise between high resolution in the valleys and low resolution in the mountains.
What I am trying to do is possible and one way or another, I will achieve my goal, even if it means learning Ruby and writing my own plugin. I am a programmer ya know, just not in Ruby.
@bjornkn said:
As advertised on this page currently there is {SNIP}
I can appreciate that you want to make a few bucks but I've already made it very clear that I am not interested in buying a plugin at this time. Using pretense to lead into a sales pitch isn't going to change my mind. Besides, I am not fully convinced that your plugin will do exactly what I need to do.
Finding free solutions may not be easy, especially when they are buried under a mountain of advertisements or misleading "free" solutions that aren't really free but don't tell you that until you download and try them, but truly free solutions are out there and I fully intend to find them.
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@mac1 said:
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.
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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
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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
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@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.
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