Halo effect around objects when rendering image..

[dylanlester1]

Still relatively new to Vray. This is my first project doing some post-work. I'm getting an issue with some of my objects having a weird halo around them and not sitting well with backplates when combined in Photo Designer.

I've combed through the forumns and I've found that I should be rendering against a black background?

 

"But what you should have done in rendering, is to render against black background, without any additional AA filter." - Juraj Talcik

 

http://forums.cgarchitect.com/77167-how-remove-halo-effect-alpha-channel.html

 

How do I go about doing this?

[Chris MacDonald]

Well, if you're using HDRI/dome light to light the scene you simply tick the "invisible" option.

[dylanlester1]

Well, if you're using HDRI/dome light to light the scene you simply tick the "invisible" option.

 

So should I be rendering against a blank background and not the HDRI?

 

BTW, what's the preffered GI engine for external renders with lots of foilage these days? Brute force or Irradiance?

[Greg Francis]

This may not be relevant but I always make sure the Environment Map under 'Environment and Effects' has been copied over to the GI Environment slot and the Reflection/refraction Environment slot in the Vray settings. Additionally that the map under Environment and Effects is unticked. This issue is specifically for halos around objects that are against the background.

[dylanlester1]

This may not be relevant but I always make sure the Environment Map under 'Environment and Effects' has been copied over to the GI Environment slot and the Reflection/refraction Environment slot in the Vray settings. Additionally that the map under Environment and Effects is unticked. This issue is specifically for halos around objects that are against the background.

 

I've always been confused by what this actually does (environment and effects slot)

I loaded my HDRI like normal but it also instanced into this slot. Every tutorial I've seen - they remove it completely. Which is what I've just done and I think this fixed my issue. I'll know tomorrow when my render is done.

[yp]

..halo around "objects" or alpha mapped images like leaves??

 

A picture would help.

 

If its leaves then a background closer to the later comp color is better - but mainly check the image with alpha channel may not be set on pure white background, white line will bleed through otherwise.

[dylanlester1]

..halo around "objects" or alpha mapped images like leaves??

 

A picture would help.

 

If its leaves then a background closer to the later comp color is better - but mainly check the image with alpha channel may not be set on pure white background, white line will bleed through otherwise.

 

This is the issue I'm having. Black background to make it easier to see... i'm using HDRI in vray dome light. Should there be anything in the enviroment slot? (8)

 

Edited May 23, 2017 by dylanlester1

[dylanlester1]

Could somebody school me on this. It's about time I learnt it properly. Please don't link me to Vrays website - I've read it countless times. I need to hear it from somebody who can dumb it down a bit so I can understand properly.

 

When would I use a HDRI in the Enviroment slot (8) ?

When would I use a HDRI in the GI slot?

 

I thought using a HDRI a vray dome light was all I needed..

 

All these comments unfortunately didn't help me with why I'm seeing this bluish outline in photoshop.. :-(

[dylanlester1]

Here's one with the backplate of the HDRI image I'm using (peter guthrie's). So I can get some good results by increasing the brightness of the backdropbut it's nearly white when I do this and loses the colour and definition..

[Francisco Penaloza]

There are many ways to skin this cat really.

From my experience, using a black background or image background will depend on how much you'll change the background in post.

It is OK to use the default Sun/Sky combo if you replace with a 'similar' sky in post. If your background will be totally different, then using a flat color such Black may help you to cut out, but I always rather use a similar overall color instead of something black. For instance, you place a black background but then you replace your environment with a white color, you'll get a black halo in that case.

 

Having said that, after applying your alpha in post, you can use the masking tools inside photoshop or any other post work software you use, to refine your cut out, do not aspect instant gratification. You need to adjust it, for instance in Photoshop you can use the mask adjustment tools, or matting tool such defringe and others.

 

V-Ray also give you the option to do some tweaking inside the render, For instance, you can place an HDRI in the 3dMax regular background, but you would like to have a different background for reflection, in that case, you can use the background overwrite inside V-Ray pannel. You can refer to the V-Ray manual for more explanation on each possibility.

 

But please refer to the manual to understand what they do and when to use them, just following tutorials will only confuse you because each artist works differently. Some people rather use those VRay background overwrites instead of using Max default background, other use a Dome light, and overwrite everything anyways (never understood that, maybe they saw it on a tutorial )

 

There are many combinations, but what to choose will depend on what is your goal and what are your problems, but to decide you need to understand what are your options, and they are all well explained in the 3D Max manual and V-Ray manual.

 

Hope this help you.

Fco.

[yp]

[ATTACH=CONFIG]55477[/ATTACH]

Here's one with the backplate of the HDRI image I'm using (peter guthrie's). So I can get some good results by increasing the brightness of the backdropbut it's nearly white when I do this and loses the colour and definition..

 

Sure it is.

 

Because you're swapping your background with an image with different exposure.

Your rendering backround will probably be way more exposed.

No mystery involved.

 

Use the techniques mentioned or stick with the rendered background - which by the way is a more natural image than comping in a blue-blue sky.

 

Otherwise use 32 Bit workflow and tonemapping methods to turn down the background's exposure.

Then keep it or comp some other in.

 

Depending on the lens lenght you're using swapping the background will get unnatural as well.

[dylanlester1]

Sure it is.

No mystery involved.

 

You must have missed this part: "Still relatively new to Vray".

Edited May 24, 2017 by dylanlester1

[dylanlester1]

There are many ways to skin this cat really.

From my experience, using a black background or image background will depend on how much you'll change the background in post.

It is OK to use the default Sun/Sky combo if you replace with a 'similar' sky in post. If your background will be totally different, then using a flat color such Black may help you to cut out, but I always rather use a similar overall color instead of something black. For instance, you place a black background but then you replace your environment with a white color, you'll get a black halo in that case.

 

Having said that, after applying your alpha in post, you can use the masking tools inside photoshop or any other post work software you use, to refine your cut out, do not aspect instant gratification. You need to adjust it, for instance in Photoshop you can use the mask adjustment tools, or matting tool such defringe and others.

 

V-Ray also give you the option to do some tweaking inside the render, For instance, you can place an HDRI in the 3dMax regular background, but you would like to have a different background for reflection, in that case, you can use the background overwrite inside V-Ray pannel. You can refer to the V-Ray manual for more explanation on each possibility.

 

But please refer to the manual to understand what they do and when to use them, just following tutorials will only confuse you because each artist works differently. Some people rather use those VRay background overwrites instead of using Max default background, other use a Dome light, and overwrite everything anyways (never understood that, maybe they saw it on a tutorial )

 

There are many combinations, but what to choose will depend on what is your goal and what are your problems, but to decide you need to understand what are your options, and they are all well explained in the 3D Max manual and V-Ray manual.

 

Hope this help you.

Fco.

 

Ok. Here's the problem. I can render out the image with the background hdri or i can render it out with no background. It looks fine with the hdri background but i need to add in some mountains. So is it possible to render the hdri seperately so i can add it as a seperate layer in PS?

[Francisco Penaloza]

Ok. Here's the problem. I can render out the image with the background hdri or i can render it out with no background. It looks fine with the hdri background but i need to add in some mountains. So is it possible to render the hdri seperately so i can add it as a seperate layer in PS?

 

Why would you render a background image that you already have???

anyways the answer is yes, there is a pass only for background.

[dylanlester1]

Why would you render a background image that you already have???

anyways the answer is yes, there is a pass only for background.

 

To match the exposure??

So i dont get that weird halo going on i have now. Even YP said to stick with using the rendered background as its more natural.

[Francisco Penaloza]

it is an HDRI I am pretty sure you should not have any problem to match the exposure if you used the same image to lit your scene.

I think you are underestimating the possibilities in Photoshop.

 

Also, you could use planes with background images and place them inside your 3D scene, then you don't have to worry to replace images in the post, I do this from time to time and it works just fine. One step less in Photoshop.

 

Go to Evermotion.org and buy one of their scenes, you can buy a single scene no need to buy the collection.

Just get one and take a look how the place then scenes, they use domes and planes sometimes a few of them to use them as the background of the images. Or you can take a look at their tutorials, they explain the same thing.

This method may work better for you.

[dylanlester1]

it is an HDRI I am pretty sure you should not have any problem to match the exposure if you used the same image to lit your scene.

I think you are underestimating the possibilities in Photoshop.

 

Also, you could use planes with background images and place them inside your 3D scene, then you don't have to worry to replace images in the post, I do this from time to time and it works just fine. One step less in Photoshop.

 

Go to Evermotion.org and buy one of their scenes, you can buy a single scene no need to buy the collection.

Just get one and take a look how the place then scenes, they use domes and planes sometimes a few of them to use them as the background of the images. Or you can take a look at their tutorials, they explain the same thing.

This method may work better for you.

 

Peter Guthries HDRI images come with the raw image, HDRI and a jpeg backdrop. I'm assuming I could use the raw image in photoshop as a background and adjust exposure that way.

And yes! That's a great idea regarding the Evermotion scenes. I think I'll do that- it will come in real handy to understand things a bit better. I'm also going to a Vray masterclass on Monday with Grant Warwick and one of the guys from Chaos Group.

[yp]

You must have missed this part: "Still relatively new to Vray".

 

No, I didnt.

 

Nothing to do with VRAY.

 

It's basic photography.

Take a picture of whatever object you like against a visible sky.

It will most likely be underexposed with a visible sky or visible but with an overexposed sky.

(As long as you're not using a preprocessed HDR function in your camera).

 

That's exactly what you do in VRAY.

 

Basics of photography

 

Once again, choose one of the many possiblities mentioned.

Dont know if you've looked into the 32 Bit tonemapping method I proposed.

There are some free tonemapping softwares around, maybe some even process exr or hdr files, probably they do process unclamped 32 bit tif.

 

Another approach is the processing of your rendering within the VRAY frame buffer, probably you can recover information in the overexposed areas as well. Then its not pure white outline around your matted image but closer to the later comp.

 

If there are mountains (I do read) maybe a blue outline will still be not the best choice, so go for the other methods instead (matting options in PS, shrinking the mask selection by a pixel, or others)

 

[dylanlester1]

No, I didnt.

 

Nothing to do with VRAY.

 

It's basic photography.

Take a picture of whatever object you like against a visible sky.

It will most likely be underexposed with a visible sky or visible but with an overexposed sky.

(As long as you're not using a preprocessed HDR function in your camera).

 

That's exactly what you do in VRAY.

 

Basics of photography

 

Once again, choose one of the many possiblities mentioned.

Dont know if you've looked into the 32 Bit tonemapping method I proposed.

There are some free tonemapping softwares around, maybe some even process exr or hdr files, probably they do process unclamped 32 bit tif.

 

Another approach is the processing of your rendering within the VRAY frame buffer, probably you can recover information in the overexposed areas as well. Then its not pure white outline around your matted image but closer to the later comp.

 

If there are mountains (I do read) maybe a blue outline will still be not the best choice, so go for the other methods instead (matting options in PS, shrinking the mask selection by a pixel, or others)

 

 

I get what you're saying, but maybe I didn't explain my skill level well enough in my initial post. I know you're only trying to help, but I have to be honest. I have no idea what 32-bit tone mapping is or processing .EXR or .HDR files. I will look into it - i promise. But at the moment, I just don't have time to get into all of that. I only have just over a week to submit my project and I'm just trying to get a simple answer as to which way I should go.

 

I think i created some confusion in this thread because I've actually been saving my renders out as .PNG files. So there is no background. I've only just realised that I should be saving them as .TIFF or .TARGA files and that will include my background! So that's half my issue fixed. My only issue now is that I have blank space in the render where you can see into the distance. Look at the attachment for what I mean..

[yp]

Yeah, no problem Dylan, I know it's a lot to discover and sort out.

It might look like a bit of a bombing to tell about 32 bit, tonemapping and so on - but actually it's not THAT much and it will help you a lot if you know about those things and the techniques to handle them and use them for your own.

 

To clearify your last message:

 

PNG (as well as many other file formats, even then ones you mentionend, you just didnt save it with transparent background..) files CAN contain alpha information, they dont necessarily do. Just as a sidenote. A JPG eg will contain your background - or a different color, but never be transparent in eg. Photoshop.

 

But to answer your question - Peter Guthries HDRI are only a semi sphere, the lower half of the image is black. That is what you see.

But still, depending on which image you're using, check if your VRAY dome light options are set to full or half sphere (half is standard I guess).

 

Solution: plant more trees to cover up the holes.

Or place images behind as mentioned by Francisco.