Fine Details Blurry in C4DtoA

[the-dude123]

Hi,

I'm trying to render a large scene with trees, bushes, etc. I've got about 1,000,000 wheat bunches scattered over the terrain (as Arnold Procedurals). Problem is, Arnold doesn't seem to be able to resolve the detail properly.

I've tried increasing the render setting (AA, Diffuse, Specular, Transmission, etc), the camera samples, the light samples. DOF is NOT on. I'm not sure whats causing the issue.

Any suggestions would be great. I have included images below. Thanks!

[thiago.ize]

Are you using curves or points? If so, disable the min pixel width (it should be disabled by default). Are there textures? If so, those can make it blurry too, in which case there's a few ways to fix that. Otherwise, can you provide us with an image with the camera zoomed onto one of these wheat bunches so we can see what it looks like?

[the-dude123]

Hi,

Sure thing. Picture of close-up below.

Yes, there are textures on the wheat.

Not sure what you mean by "curves or points"?

[the-dude123]

Pictures below

[thiago.ize]

It sounds like the wheat isn't high res geometry and instead are textures of wheat on top of some coarse geometry? In that case, try increasing the global options.texture_max_sharpen from the default of 1.5 to something higher like 3. You can set it to a huge value like 999999 if you just want to do a quick test, but beware that the higher you set this, the more memory is needed for the textures, so for complex scenes you want to show some restraint. Then, combined with this you'll probably need to raise the camera AA samples. See https://answers.arnoldrenderer.com/answers/928/view.html for some more info and another thing to try (texture_conservative_lookups set to false).

Curves and points are types of shapes, similar to how you can use triangle meshes. In c4dtoa terminology, a points object is I think called a Particle and arnold curves are Hair objects and Splines.

[the-dude123]

Hi,

I made the changes to the Options (texture_max_sharpen 9999), it did not help, unfortunately.

I turned off textures to isolate the problem and even the bare geometry still has the blurry effect.

See pictures below. I have also included a pic of the wheat geo for reference.

[lee_griggs]

Can you render the wheat close-up? Motion blur isn't enabled, right? Can you upload a simplified scene?

[xebajac]

If this is the IPR, increase the scale if it is less than 100%

[madsd · Accepted solution]

You post 3 images in 1920x1080.
This is far from enough resolution to bring out the details you want on those tiny haris seen so far away, render to 5000x2600 or so, then scale down if you need to. It's always healthy to crank out large resolutions to overcome detail problems.

[thiago.ize]

It is indeed possible that it should look "blurry". Mads suggestion of rendering at high res (maybe just a small region so it's fast) and scaling down would be a good test of this. If it looks good at high res and then goes back to being "blurry" when you downres, then there's nothing actually wrong. In theory, if you use the same filter in arnold as you used for scaling down the image, combined with a high enough texture_max_sharpen and more camera AA samples, these two operations should give identical images.

[the-dude123]

Lee: Yes, wheat renders fine close-up. Motion Blur is OFF. Scene file is difficult because the wheat is Arnold Procedural with file paths and all that fun stuff.

xebajac@: IPR is 100%

Mads: See below for an image that was render out at 5760 x 3240 and conformed to around 1080 in post.

[madsd]

Its better.
I can zoom 500% and start to see actual details, although blury on the front pieces. But again, these things are tiny in your image still.
Try take a photograph from same distance and zoom in and check sharpness on an item.

I took a measure on the last image here, and the middle straw are only 35 pixels tall! you cannot get a lot of detail into such a small area.

[madsd]

What you can do, is to use an unsharpen mask with a pixel radius of 0.3 and give it some strength. You can sharpen your image post. It will give you sharpness to some extend for free. but you cant get around that these are micro items, so you will get full entrophy at a point regardless.

[madsd]

This is your stick on last render. I can count the pixels its wide.
Lets look at the vegetation around it, its black and grey pixels bordering to a hash noise, impossible to detect this stick stands on a field, because the pixel density is very very very low in that particular area.
You have no problems close up, so things in the background will become scrambled, thats how it goes. And if you want more detail up front you ask for something impossible, we cant put more info into pixels than it is wide and tall.
Except, cranking resolution up.

[madsd]

You cant have small Full HD image with ultra fine details from far away, this does not exsist. A pixel will in the end 1 km away cover 3 meters of field coverered with plants, so these plants will never ever render anything but the color assigned to that pixel which is an average of everything on that direction at that particular point

[madsd]

This how "sharp" and define this bush thing on the side of the road is on this image.
Big image looks perfectly normal, something I guess you want to resemble.

[the-dude123]

Hi Mads,

That all makes sense. I'm trying to render an extremely large area because I've got large objects which are the focal point of the scene. The white stick/cube in the images is 6 feet tall. The bushes just looked a bit strange, but maybe not too strange when compared to a real 1080p shot from a drone:

https://www.dropbox.com/s/lgbzqhubby2hz60/Screen%20Shot%202019-10-08%20at%201.35.18%20PM.png?dl=0

Full image of wheat from C4DtoA (5760x3240 144DPI):

https://www.dropbox.com/s/lqy571wjug4apwe/5760x3240%20144DPI.exr?dl=0

[lee_griggs]

This looks fine up close. I am wondering if it just looks odd from a distance because the wheat instances are all the same object, using the same orientation. I am sure it would look more 'natural' if you had different clump objects with random rotation.

[the-dude123]

Hi Lee,

That's actually a good point! The wheat has been randomly scaled, but I did not randomize the rotation yet. I'll give it a try.

I was thinking about this as well...like maybe it looks strange because of some optical illusion create by using the same object over and over and over.

Thanks!