Cineversity

Hi, I have a problem with triangle artifacts showing up where I have applied a soft bump map. I tried uploading a zipped scene file with bump map but got the error: Error Message:  The file you are attempting to upload has invalid content for its MIME type. The mesh is part of a client’s product given to me in the form of a STEP file. I opened it in MoI and exported it as a OBJ file with a normals tag.

Hi Randy,

Would you mind to try to share the scene file again, just with the object and the texture you used.

I will have a look into it.

If the mime type error happens, I use another zip option, or try it later. Besides that, perhaps DropBox, Amazon, or any other of the cloud services might be useful.

I will send you an PM.

Talk to you later.

Thanks, Sassi! Here is a link: https://www.dropbox.com/s/uux2ipvwlkmm1u8/Bump map tears2.zip?dl=0
- Randy

Thanks for the file, ignore the PM then. Thank you, Randy.

The mesh is the problem, as it is not completely connected. No short cut here to fix it. To get the edge rounding with a bump map will not work.

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There are three things, with more or less impact to this:

• The mesh is not really connected. See image.

• Bump settings above 20% seems always a risk to me, to go at (+/-) 500% even more so.
(There is more to it and I hope I get the triangle explained—“bit-depth/value”, resolution and strength)

• The texture is 8bit/c and using (roughly) only half of the values. [0-58%], so 0-129 (of 256 total).

Bump maps are a fake, as you know. They take changes from one value/pixel to the next as a virtual change of the normal direction. The higher the change and the percentage, the more harder the light change is. To have only a few values (half of 8bit ~) and a high dynamic in the percentage allows for a strong contrast. The wrong action would be, to just use a Level [Ps] and “stretch” the values (as some tutorials sadly show) and switch then to 16bit/channel. The texture must be set from the start to anything but 8bit/c if such strong effect is needed, the strength shouldn’t be high, otherwise effects with a more or less tangential view to the surface are typical.
As they (bump) fake the normal direction, they work only inside of a polygon or a connected group of polygons. I they are interrupted the effect stops. The interruption seems to be the problem here in the first place. Hence I guess that is why the value is at 500%, and even then you get not a real fix, especially not as some areas are connected and so the “stripes” appear. A problem that occurs while trying to fix another one… So, let’s explore this to avoid it in the future and find a better way. Or jump to the ===== directly

I checked also the light source, as I really advice NOT to use Shadow Maps. These are as well fake and the lowest quality one can have. Especially if set up in the way I found it in the file. It had only 250x250 points, which means, as it was set up to worse case “Omni” it has a 90ºx90º field of view for that map. It is not a texture map, it is a point map. Between these points the “shadows and gradients of the result are interpolated. It didn’t lead here to the problem as the area shadow delivers with the Bump 8bit/c and -500% a similar result. (The artifacts starts at around -200%, so if the texture would be optimized, this indicates that even then a high strength value would be needed. High values are possible here (+/- 1m) to counteract blur results from MIP/SAT)

The second image shows, with the same texture but adjusted to black and white, where the area of the bump would be. To get the rounding established.

The tangential view might be not supportive here either.

The Physical Render is certainly great, but it produces what was fed into it. In this case, I have no short cut advice. The mesh is not useable, the texture is not usable and the light needs to be done more carefully. Strong words, but it wouldn’t help to sugar coat it. Sorry—anyway, not fun to do for me either (… being the messenger of bad news).

The render resolution in the Render-setting seemed to be for the Camera projection, it would be too high for that texture.

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My advice, skip the bump part all together. The change of the surface that you would like to have needs to be modeled*. Especially with that tangential view of the camera. The polygons that I lifted here [image on the left] show clearly that they are not connected, and the structure doesn’t allow for a quick fix, this is manual work, perhaps first with a knife and optimize after.

I would set up the light with an area light and an area shadow. If reflections are needed, a simple plane does the trick.

*If the mesh is fine and subdivided, perhaps a Displacer might work, which would be a fast trick.

I hope I sounded not critical, not my intention, but I guess you had hopes that it would be less effort to get it done.

My best wishes.

Sassi, sorry if I didn’t let you know my entire situation. I have been using this workflow for years with great results. For some reason this time I am getting these triangle artifacts. Yes, the bump maps are 16 bit. I made them 8 bit in my attempt to make the file smaller so I could upload to the forum.

I got rid of some points on the N-gons so that they end up being quads and the triangles went away. This is not a fix I can use because I cannot modify the model that I get from my client. Just wonder why this problem is showing up this year.

Here is a link to a sample rendering from last year that was successful:
https://www.dropbox.com/s/060nx4dlmnfj0dl/golfclubsample.jpg?dl=0

Hi Randy,

Thanks for letting me know with the 16bit/channel, I’m glad we are on the same side with this. Yes, that will make a huge difference—normally.

I have solved all the “disconnections” and even with the extreme values no stripes appear. But I can’t really see why to set this to 500% in the first place.

If you had success with it in the past, cool with me, I can tell only what I would do and what is suggested in the help content. As in:

You can enter values much higher than 100%. High values are especially useful when using MIP or SAT mapping, because these interpolation types tend to flatten the surface slightly.

My answer in a nut shell, the mesh is not continuously connected, and there the problem starts, the bump makes the problem only visible.

Why that is showing up “this year” is not something I can answer without seeing the mesh from the projects before. But load them and have a look if that problem appears there, if so, then please contact the support, as it is then an problem that I’m not supposed to handle here.

My best wishes.

P.S. the geometry is just connected, I do not even say it is perfect now, but no Bump artifacts anymore.

I have set the strength to 500% to get the amount of bulging needed to make the overly geometric engineer’s model look more like the real golf club I have beside me in my office. I keep the background of my bump files at 50% gray because I only want the bump applied in the areas that are not 50% gray. If the background was black wouldn’t that be applying a bump in the opposite direction of the white areas?

So, did you connect the two meshes so that everything ended up being quads? I did a test myself where I got rid of the “ring” of mesh and then simplified the Ngons of the remaining single mesh so they were quads. The stripes went away. Are the Ngons the problem?

Thanks for discussing this with me!

-Randy

Hi Randy,

You’re welcome, my only target is to give you as much as I can. I’m not interest in being right or to critique others (the later stresses me even). Thanks for being open minded to a different viewpoint.

The 50% gray is something that belongs to the Displacement>Centered adjustments. In Bump mapping, the change is the key. The change of the Normal direction is based on the difference of the texture and the “strength” setting inside of the bump-channel. The result of these two allow for an illusion of a surface. I mentioned above the triangle of it, as the step size between the pixels matters here as well.

If you take a sphere, and set up a very tiny specula spot on it, then use a Color shader in the bump channel and set it to 500%. the first rendering to the picture viewer with the color shader to white, then another with the color shader to black. Then A/B the two renderings. The spot has not moved. Now take a noise shader into the bump channel, with 500% as before, the specular spreads out over the whole sphere. I hope that clears the idea of black, gray and white as base color. It is the change that matters. With the strength you multiply this change only.
(With 8bit/c or 16bit/channel the steps become more defined. I mostly fight 8bit/channel since a decade, but that point was cleared above. Even 8bit/c is the delivery, it shouldn’t be at any time production quality.)

All the best

Hmm! I didn’t realize that about bump maps. Just the areas of change.

Well, I exported the mesh from MoI again with “weld vertices along edges” on. Once as ngons and once as quads and triangles. Now I have a connected mesh and still get the artifacts. Could it be something to do with the normal tag that comes along with the OBJ file?

Here is the link to the scene file. Use the previously included textures.

https://www.dropbox.com/s/wtwf7iulk9e1j2g/Bump map tears3.c4d.zip?dl=0

Thanks, again!

-Randy

Perhaps, try this one, below, but I have to admit, that I did not knew the target or the amount of subtlety you where after, while writing it in post #2. My assumption was that the target was to overcome the hard edge between the flat part and the rounding, as an interrupted flow works like a “Break-Phong”. Hence my idea that it will be not an easy fix. More information, more ideas…

I use only the Optimize function here. I left all n_gons in the model for now.

P.S.: I use underscores in file names. I got often critiqued for that, but as you can see, the Drop-Box link is always broken based on it.

All the best

I can’t figure out why the mesh now appears to render as black in your file versus the original file I sent to you. I can’t tell if there is artifacting because it is so dark. Do you know why? Have you seen it as it appears in my first post?
-Randy

Please load the replacement from above [#9] and it should be fine.

Okay, now it is lighter, but when the bump map texture is linked to the texture the triangle artifacts are back. Hmm…
-Randy

Hi Randy,

If you render with -500%, I’m not surprised, but I repeat myself here, sorry.

I tested this with animated “strength” values from 0 to -500%, and it shows up at around “-100%”, in Physical Render and in Standard Render. I do not see from 0- -500 a huge change that would really make this a valuable set up—but that is me. I think I have said and done everything I know. I will attach the animation in a follow up post.

The flat angle (tangential) might lead to a higher value distance of the bump pixel in consideration, at least that is my explanation. I have attached an image that shows how the Bump-Map works here, if the camera moves away from that “flat” viewing angle. See below. At 200% scale I see a noise pattern, and if the camera is that flat it adds up. Again, this is done with a 8bit/c image. I took that image of course, turned it into a 16bit/c and Gaussian Blurred it 12 pixel, three times, then used 10% Mip and 10% Blur scale in the material editor, and the effect was weaker.

If you need the 500% then:

You can do the following, stay with the value and set the two blur values to around 20%, it will show very little then.

OR

You get in contact with the support. http://www.maxon.net/support/support-questions.html

My best wishes

P.S.: ... as promised above, here the animation. I had set up the “Strength” on frame 0 to 0% and at frame 100 to -500%. With Physical Render first and then Standard, just to exclude the render engine as source.

On the end of this one minute clip, I explore shortly the blur settings, which eliminates pixel value “jumps” and the results speak for itself. I hope I ahve explained, explored and tested all possible options. If there is anything more, please check with the support team. I hope you get what you need. :o)

https://www.amazon.com/clouddrive/share/wKGVKPmG6PsScqZH7up46faWHJEELwoI1bgYsYFCqSn?ref_=cd_share_link_copy

Thinking about the target with the bump map here, I can only assume that a illuminated plane with a gradient (bright in the middle and dark to the edges) might would have worked much better, than anything that was used in the scene. But I never got really an idea what the target was. Perhaps a flat an wide Specular Highlight would have done the trick as well.

If the adjustment of the surface and the softness of the Normal direction was the key, the Normal Map option would be much more precise here, but harder to set up.

Just an idea:

Bump versus Normal

As I mentioned the change of values in a Bump Map is the key. The image from the “Help Content” illustrates this with the arrows. No change—arrows are parallel. In this way thy have an orientation. It is not absolute for a single point alone, the neighbors push and pull—roughly said.

The Normal Map is different, and nearly impossible to create manually. Each color channel stands for a rotation, HPB, but also dependent on the settings, world, object, etc. Before I even drift into nerd-land with this, I like to focus on your use (if I got this after this long thread correctly). The bump map is smooth and helps to get a little bit more shape and life into an object. If you bake a Normal Map, one options is, to blur each channel a little bit, well experiment with it—how much. This sets an absolute Normal direct for your object and avoids what happens above (compressing the texture space based on a flat camera angle, and increases so the effect locally). Normal maps do not have that kind of weak-point, they are pin-point precise data, but you can blur them, perhaps, with a mask (find edges, filter max, blur). Then blur all so softer edges, but all other stuff gets in the mix as well.

The problem here is sometimes given in edges that are not connected with others. have an eye on such.
Enjoy

https://www.amazon.com/clouddrive/share/OL6rSD1T95ogVZNtqfK4V0Jl3BRlWSa165uyn6HVXfy?ref_=cd_share_link_copy

P.S.: activate the Reflection to see how strong the Normal Map works on the Sphere. I have three states of the normal texture in the tex folder.