Unfair and set-up comparisons by xNURBS

If I may, XNurbs is ultimately only a better “patch” than Rhino’s. Nothing so revolutionary.
The Rhino patch is outrageous after seven releases now …
Xnurbs will not be better than some Rhino tools (sweep 2 and match) but you can immediately close a hole in continuity at least in G1, without having to resort to various adjustments and various steps.

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While xNURBS could achieve G1 and sometimes G2 at the boundaries, it’s the internal flow of the surface which is equally important. Imagine a wavy surface that blends to the adjacent surfaces at G2 continuity, but is too inaccurate at the middle portion. :slight_smile: This is what happens most often with the xNURBS patches. It may not be THAT obvious on the official videos on YouTube, because the camera rotates all the time, but a close inspection eventually reveals the truth.

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Try this. I agree with you, Bobi!
Rhino Surface test1.3dm|attach
ment
(15.3 MB)

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The larger blend surface in that file has some imperfection. :slight_smile: The ! _RemoveMultiKnot tool fixes it. But still, the flat surface next to it is split improperly, thus it generates an issue with the blend surface to the wavy trim curve. It’s evident with the Curvature graph.
What’s the purpose of this particular example? :slight_smile:

I suggest to use the following settings for the analysis mesh, because the ones that come with the file you provided were too dense and heavy for my poor video card: Nvidia GTX 1660Ti.

This is a quick fix of the geometry and some basic filling of the hole, but it’s not optimized and has plenty of flaws. I can’t stand G1 models with sudden change of the zebra stripes. I much prefer smooth blends. :sweat_smile:

Rhino Surface test1.3dm (6.7 MB)

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Another example where xNURBS for some reason fails to do its job, despite the clean geometry with G2 continuity across the input surfaces and curves. Before the video, I tried picking the curves and surfaces in any combination, but no matter which way, it always refused to build a patch surface at the moment I changed the tangency for the input edges from G0 to G1 or G2.

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@XNurbs I modeled a similar surface that Bobi is showing in his video, see attached. How would you recommend building the tip in XNurbs? I tried to make it work but got similar results as the ones you see in Bobi’s video. Also the top blendsurface that connects the two sides, can’t be exactly built with XNurbs, the transition becomes more abrupt:

lofted_tip.3dm (2.3 MB)

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@Gijs , Thanks for your model.

We did not reply “Bobi Rhino_Bulgaria” because we think he/she may be a troll: When we added xNURBS to Food4Rhino, someone immediately used a fake ID to give 1-star rating on Food4Rhino. After the troll was identified and 1-star rating was removed, “Rhino_Bulgaria” came into our sight. We have no idea how many 1-star ratings “Bobi Rhino_Bulgaria” contributed to xNURBS on Food4Rhino (anonymously or using fake IDs).

Quote from the xNURBS manual: “When selecting the Optimize for Quad-Sided Surface option, no internal constraints is allowed.”

The manual clearly explains why. If “Bobi Rhino_Bulgaria” did read the manual, then I would say “Rhino_Bulgaria” intentionally did this.

It makes it very difficult to understand what “Rhino_Bulgaria” did. We figured out what’s going on from the following picture. Why didn’t “Rhino_Bulgaria” change to the 100% white color?
image

The car side mirror demonstration only shows a quick rebuild. The curves are quickly extracted from an existing model by a designer and then projected to a plane so that they are on a plane. This may be the reason why the curve quality is not ideal. We did not even check the curves. So how could anyone intentionally “create” the curves? During the speed design, no one want to spend time to carefully design or modify the curves. For the final production design, designers generally cannot modify the existing geometries. For a student design, you can easily ask ideal “input”, but for anyone who worked on complex products, e.g., automotive model or airplanes, it may not be the case.

Again, the car side mirror demonstration only shows a quick rebuild or speed design. If you really want to see the model created by professional designers, please see this model.
image
The model is designed using xNURBS in Rhino 7. Click here for the video . As said in the video, “When surface reflections don’t line up or produce unwanted artifacts, I use xNURBS to rebuild those smaller sections until I achieve the surface quality I’m looking for.”

@Gijs The following GIF shows how to generate the blending surface you want - add two curves to precisely control the shape.
Blending

The following GIF shows how to do the “lofting”.
Lofting

Quote from the manual: “If Show preview does not show the correct trimmed surface, then it means that XNurbs cannot deduce the correct surface from the input constraints … Simply adding some (boundary or internal) constraints will provide XNurbs with additional information to deduce the correct surface.”

For this model, to generate class-a surfaces, you need to split the patch into smaller patches.

This video explains the idea.

@Gijs, There is one mistake in your model:

This is called a singular point, where the surface normal disappears. Singular points cause many troubles, e.g., the screenshot below, and software developers and professional designers try their best to avoid such a design. I am sure you are a professional designer and won’t present such a design to your customers.

@Gijs If you wish to discuss more, please start a new thread and don’t use this thread.

Oh boys
Calling Bobi a troll is the insult of highest order showing you didn’t do a basic check.
He is one of the most respected members of this community, mentor and teacher.
Whatever you write as an answer is loosing credibility afterwards.

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well that entire topic title is a little hostile i would say not to forget, bobi seems a bit pissed off why ever, i can see why xnurbs would think so, but you are right i would not categorize bobi as a troll ever and i hope not that he is a double spy acting in complex matters :smiley:

xnurbs is hooked tight on believing to be haunted by jealous trolls from the competition or similar whatever that means.

back to the topic. @xnurbs please make your plugin for mac available finally.

:pray: Please, both sides, rage is not helpfull here, pull the handbrake, no accusations and back to the pragmatic discussion.

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I’m sorry, but your false assumptions about who is a troll are completely wrong. That must be another person on Food 4 Rhino, not me. I would never rate someone’s work or software with 1 star, even if I’m not satisfied by the results. :slight_smile: I much prefer to invest some time to explain the pros and cons of some product rather than voting with 1 star. I started this topic, because xNURBS is advertised with huge amount of hype and overpromising, but in practice in many cases it clearly underdelivers.

I recommend you to focus on improving xNURBS and advertise it in a more honest way, which also includes proper comparison with Rhino’s own tools. In your videos you (or someone related to you) often tend to use purposely bad geometry (split edges with tiny jaggies, curves overloaded with unnecessary amount of random control points etc), in order to make Rhino’s tools perform badly and make xNURBS shine in comparison in those wrong situations.
Also, as I mentioned in my original post, you always use the very basic default settings of “Sweep 2 rails”, “Blend surface” or any other Rhino tool and don’t invest time to try their other options, because that’s another easy way for you to make them perform less effective in comparison, unlike the time you devote to optimize the settings to build a surface with xNURBS. It’s like driving a sports car like Ferrari on a rough off-road terrain and then claiming that it performs poorly. Of course it will, because you purposely drive it in a wrong way. This is why the topic is called Unfair and set-up comparisons by xNURBS. :slight_smile:

Looks like either your Rhino is rendering this area badly, or my Rhino does it nicely, because the model uploaded by @Gijs looks like this in my Rhino 7.

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bobi, you are extremely confrontative and i dont see many reasons why you would do that, other than being a double spy for real :wink:

many of his user cases are generic, not specifically done purposely to show how bad rhino performs. seriously calm down.

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Why would you use the word “professional” while you write about that particular 3d car model? Send it to me and I will easily point at least few dozen areas with bad surfacing on it. Many of them are easy to spot even in the YouTube video, but I can show you all the wavy areas and lack of good continuity using Rhino’s analysis tools, in case that you wonder how professionally made is this particular model.

As for the curves on your mirror model that were overly populated with random control points in uneven distances, a simple use of one of the several tool in Rhino to simplify and rebuild the curves witinh the desired tolerances will give you much nicer input curves to build better quality surfaces with xNURBS or any surfacing tool in Rhino. It just takes a few seconds to press the proper icon in Rhino to fix those improper curves. The surfaces made with xNURBS on that mirror have several wavy areas and inconsistent flow.

I watched the video several times, but I’m unable to see a single xNURBS surface that’s able to achieve even G1 tangent continuity in some areas. Every single surface in the video tested with the Zebra analysis has a certain amount of waviness and inconsistent flow, as well as noticeable lack of smooth transition between the surfaces. Don’t get me wrong, I’m not trying to say anything about the professional designer who created that model, I only comment on your bold claims about the quality, because the Zebra analysis clearly reveals deviations that are in contrast with the promise. If you try Rhino 7’s Edge continuity tool to examine that particular model, it will conveniently show you where the greatest deviations are located.

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@XNurbs I don’t get that weird zebra on the surface I sent either, and yes, I am well aware about singularities. I know when it is a problem and when to avoid them. In this case however, it is not the point of attention. The surface can easily be over-modeled and trimmed. This discussion is to get the best possible surfacing with the tools we have. So far the loft gave the overal best result in the shortest time, which is also an important factor. This is what I like about XNurbs the most: that in many cases you can have a very good result in almost no time where manual surfacing might be able to take it a step further but at the cost of a multitude of the time needed.

The method you propose gives an non symmetrical surface and with neither setting I can get a good flow:

I did try other ways though to get a better result with XNurbs. This one is quite interesting where the lower surface is a blend surface and then trimmed, then filled with a Xnurbs with an additional guide point:


but the result is not 100% good flow.
blendsrf+xnurbs__tip.3dm (284.8 KB)

This one is a variant that works a lot better, this time the blend surface is trimmed to leave a 4 sided gap to fill with an XNurbs surface:


blendsrf+xnurbs__tip2.3dm (377.9 KB)

Overall it would be nice if XNurbs allowed for more aggressive surface flow to create more G3/G4 like transitions. In other words, we need more ticks on the lowest slider (at the right side of the spectrum) so that we can create similar surface tension as we can with BlendSrf.

The attached files all have history enabled for the XNurbs surfaces to check them out.
Btw: the blend surface was a G4 blend

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One more…

blendsrf+xnurbs__tip3.3dm (243.6 KB)

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This GIF shows the weird zebra of singularities. Because of singularities, the quality and shape of the surface can be unpredictable and unreliable. I don’t think you could find such a design in the final car body for production.
Lofting1

To get Class-A model, I suggest that you split the surface based on curvature. However, this is not a typical surface like a car body. The slitting is useless for common surfacing.

QuadSided.3dm (242.3 KB)

The model above is QuadSided.3dm and the video is generated from the model. The original model is created by Alias or Catia, and it is a part of an automotive body for production, i.e., the final design.

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Yes that’s a very tiny piece of a Catia model I sent to you :wink:

anyhow, the surface with singularity is not a surface I would call a final surface, but again, this was not the main concern. I’d rather have one point off than a complete wobbly surface, the point is easy to fix by slightly overmodeling the surface. We are looking for a way to create the tip of that surface with Rhino and/or XNurbs tools. Based on your screenshot I made another one which so far seems to give best flow (trimming the loft and filling the remainder with an XNurbs surface.


lofted_tip+XNurbs.3dm (280.7 KB)

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Yes, this is definitely better than the original one.

I am sure you won’t present such a design to your customers. You are a professional designer :smile:

@encephalon , I would ask the money back if this were a paid job. It only shows Rhino + xNURBS creates a better model. :wink:

We posted a message to another thread and asked Rhino to publicly reveal the guys’ names who vote xNURBS on Food4Rhino. The following is a part of the message:

Currently, xNURBS rating on Food4Rhino is 2.8 - genuine xNURBS users give 5-star rating on Food4Rhino and trolls use fake IDs or anonymously give 1-star rating. In other words, nearly half of rating are 1-stars and another half are 5-stars on Food4Rhino. For anyone with basic statistics knowledge, it means the rating on Food4Rhino is forged. In plain language, trolls are manipulating xNURBS rating on Food4Rhino… We have 18 votes in total on Food4Rhino. Those guy(s) didn’t realize that, with their “work”, we only have 1-star or 5-star rating on Food4Rhino, which makes it “awkward”.

The xNURBS development benefits the whole Rhino community and Rhino users. From the simple fact that nearly half of rating are 1-stars and another half are 5-stars on Food4Rhino, it is obvious that trolls are attacking us. Apparently, someone try to discourage us from further developing xNURBS for Rhino users. Without xNURBS, professional designers would use other software (or Rhino competitors) to design a production automotive model, e.g., the model below. Some person(s) are upset with the fact that, with xNURBS, talented industrial designers can use Rhino to deliver super impressive automotive models in a very short period of time. In my opinion, the trolls may actually work for Rhino’s competitors and it is Rhino’s job (not ours) to deal with them. Bob, could you ask Carlos to publicly reveal the guys’ names who rate xNURBS on Food4Rhino? I don’t see any reason why someone needs to use fake IDs or anonymously make 1-star rating.


The automotive model is designed using xNURBS in Rhino 7.

I’m also curious to reveal the users who vote with 1 for the xNURBS patch tool, because then the @XNurbs XNurbs user will publicly apologize for calling me a “troll”, and will give me a free license for his plug-in as a compensation for his manner. I will also continue to help him make his plug-in better, by pointing out the errors that it produces.

Since the same user focuses on writing about quality, professional designers and asking money back for poorly executed job. The 3d car model posted above fails to obey the majority of industry-standard rules, despite the shiny renderings that may fool some people. If you want to understand what makes a car model to be considered good quality and manufacturable, here are the major rules that all truly professional designers follow:

  1. They make sure the flow of the surfaces across the car’s body is consistent and free of any waviness (my post above including the screen-shots taken from the video posted by XNurbs clearly show the true nature of its surface flow);

  2. They maintain constant radius for the door windows (be it single-curved or double-curved), in order to make it possible for the latter to slide along the window rails;

  3. They make sure that the wing mirrors will let the driver see behind the car, following the official law requirements. This is especially important on cars with very wide rear fenders. Tip:

  4. They would never design extremely low doors that would collide with the nearby sidewalk (unless suicide doors are being used).

  5. They make sure that the tyres will not collide with the wheel well arches while moving across the suspension stroke.

  6. They set at least 120-150 mm ground clearance on most passenger cars, but never less than 80 mm even on the most exotic sports cars, because of 3 main reasons: a) the bump stops in most countries are up to 70 mm tall; b) the ground clearance decreases by at least 10-20 mm while 2-5 people sit in the car; c) the front end dive a lot upon high-speed cornering or sudden braking.

Fix: “Without xNURBS, professional designers would use PROPER MODELING TECHNIQUES to design a production automotive model.”

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@XNurbs I do like XNurbs, I have used it in many projects already. I’m not a car designer though and have never needed to produce surface models for exterior car parts, only interior panels.

I’m just generally interested in creating high quality surface models that are as clean as possible.

You and I have had many email exchanges already and I helped you improve XNurbs with sending models and feedback. I hope you can stay this open towards feedback, as that’s the best way to make things better.

I don’t quite understand why you think @Rhino_Bulgaria is a troll. He’s a very high respected member of this community and has shared a lot of his knowledge with us and continues to do so.

In fact his proposal is the best offer you can take: let him use XNurbs and give feedback on how to improve. He’s one of the very few people in the field that has proven production models made for exterior car parts in Rhino.

The car model you show in the video is Not a professional production car model, it’s a concept study and as already pointed out has many surfacing flaws. Totally fine for a concept but not as production surface data.

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