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count_bobby

Archviz demystified II

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As promised in the oder Archviz demystified topic I hereby want to open a new one. I encourage everyone to post images here that are relevant to this topic, be it interior or exterior shots. As posted in the first archviz topic I am not very used to do archviz in Houdini (or in any other program) , doing engineering visualizations most of the time. Though I am not an archviz guy I love to do it from time to time because I think it is very easy to get some decent results with Houdini out of the box without too much tweaking of shaders or lighting.

I would like to see some other archviz done in Houdini, be it low or high level work. To encourage those who maybe think that their skills are not enough to post images here I will come forth and post one of my first "archviz" images I have done many years ago (in Blender). This image is so bad, it will be hard for anybody to post something worse ....

09_wohnzimmertisch+(2).JPG

I downloaded THE classroom scene just to have a starting point and began to bring it into Houdini. The first Image was rendered using 4 area lights in the windows with half distance attenuation, one sun light and an environment light. The render settings where:

Pixel Samples: 12 by 12

Min Ray Samples : 4

Max Ray Samples: 9

Noise Level: 0.04

Reflection Limit: 4

Refraction Limit: 2

Diffuse Limit: 2

The Render Time was about 1 hour on an 8-core AMD machine.

HR01_comp.jpghttp://2.bp.blogspot.com/-aUL1bj2BPuo/UVcY9dnOq5I/AAAAAAAAAgc/IttARxshFtA/s1600/HR04_Comp_Portal.jpghttp://2.bp.blogspot.com/-aUL1bj2BPuo/UVcY9dnOq5I/AAAAAAAAAgc/IttARxshFtA/s1600/HR04_Comp_Portal.jpg

The second Image was done using Portal Lights (instead of the 4 area lights used before) and one area light on the right side of the room to increase the overall light level. I also pu a sun light in the scene. The render settings where the same as with the previous one, but the render time went down to just under 30 minutes which has something to do with the portals I presume.

HR04_Comp_Portal.jpg

So if anybody has some tips on how to aproach archviz in Houdini or has something to show for himself I would be very pleased.

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Have you tried to add an Indirect GI Light? Photon cache of the indirect light can speed up the render and reduce noise.

What are your Mantra sample settings?

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@count_bobby :

Awesome, it's great to see more guys try to crack the archviz myths using Houdini. I'm still actually try to crack it, once I've got enough time now, quite busy busy these days.

My suggestion would be by :

1. Applying a correct linear workflow to the scene will reduce overblown or over expose area which will lower rendering times due to less samples needed to render overexpose area.

2. As old_school suggested, on my recent test GI Light, do speed up the rendering, reduce noise and increasing light reaches slightly for multibounce PBR.

Cheers..

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I've also been trying to work on some indirect lighting and caustics in Houdini.

http://imgur.com/a/7iPYu

I was ideally going for nice sharp caustics and shadows from glass, the first image in the link is what I was going for, which is a vray render. The second image is a render i got out of pbr.

I'm running on a i7-2600 with 16gb ram. 2M caustic photons and 2000 filter samples on the indirect light. 12 minutes for the photon map and 14 minutes for render.

Some things I am confused about:

The light shape and position has a lot to do with the caustic pattern that comes out of the glass (I was using a single area light), however the index of refraction has no influence of this pattern.

I couldn't find any way of having the shadows correlate with the caustic pattern, causing a really unsatisfying shadow on the render which looks silly and without a shadow also looks peculiar.

With indirect lighting for archviz, the third image is done with just a portal light directing the houdini preset HDR (DOSCH_CARB_04SN_lowres), 3 diffuse bounces, and an area light causing that sharp shadow. The diffuse bounces really take a toll on the render though, causing a lot of noise, which requires high render quality to smooth out, exponentially increasing render time :( I haven't been able to get a good setup going with the GI light unfortunately, either causing errors or not showing at all.

I did more tests with the 3d lighting challennge dinosaur museum.

http://imgur.com/U38vQCs,Qu2gJE7#0 the second image i cut short of rendering @ ~65%

the settings on the first render:

PBR

7/7

min 1

max 64

noise .01

reflect / refract / diffuse @ 10

color limit 10

Again simply a portal light directing a preset HDR. Would love some insight though into using the GI to speed up the render times for similar quality.

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Photon maps, yeah how about those...

I'm not a fan, their implementation here throws a wrench into the simplicity of the physically based rendering workflow, requiring you to fiddle and re-render, fiddle and re-render, and in the end I'm never sure if the results are the same as what I would get from path-traced caustics.

Looking at your renders, are you using a linear workflow? Your shadows just seem really dark.

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Yeah, I think all the renders had the gamma at 2.2 (otherwise a lot of light was black in the shadows), though my lighting was pretty thrown together, the shaders were just default that came from the scene, or just basic mantra surface shader. Can you do path traced caustics in houdini? That might allow for the caustics to create accurate shadows then... using the faux caustics for shadows looks terrible in my opinion. I switched the PBR to all paths, from specular and diffuse paths, if that makes a difference. It's a very weird setup mixing both diffuse bounces and photons for indirectly lighting scenes but it does work partially, just... not how i'd like for it to be setup. Will post more tests soon.

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Yep, you can do path-traced caustics. Setting All Paths is how you enable it, however you will want to increase the Color Limit from 10 to something like 1000, otherwise your caustics will be muted. As you may know, path-tracing is generally not very adept at handling caustics. For reference I canceled this render after 24 hours.

post-37-0-69909800-1365282360_thumb.jpg

Edited by DaJuice

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Houdini's Mantra is not only a lot faster, but also there's a big update in the manual.

http://www.sidefx.co...r/understanding

http://www.sidefx.co.../render/quality

I was happy to read this bit :)

Physically Based Rendering (PBR) should be your default choice for almost any rendering.

By the way nice renders count bobby. I like glad to see these threads and hope more people participate.

This is not exactly archviz, but I've started working on a scene that's meant to be sort of a playground for PBR and a backdrop for tweaking and vetting new materials. I plan to create a few buildings or structures where you can test different lighting setups. This one for example was modeled with the classic sunlight-through-window shot in mind.

http://img.photobuck...02.jpg

Though it needs some decent materials for starters...

Edited by DaJuice
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Today I was trying to set up a simple scene with a hole and an environment light, I'm not sure why but some of my edges are quite bright.

Anybody ever run into this issue before?

post-6960-0-93309800-1366610160_thumb.pn

bright_edges.hip

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Guest mantragora

Portal Light should give you better results. Less noise, faster render time and no bright corners.

EDIT: Some settings on your ROP are a little overkill for this scene. Attached image shows the same scene rendered with portal vs environment. I also lowered some settings and as you can see with portal I get clean image while with environment it's noisy and renders a lot longer.

post-7494-0-34105000-1366612655_thumb.jp

Edited by mantragora

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Guest mantragora

What I'm curious is, how to use portal/indirect lights to get the same result like with environment/indirect pair. I'm getting a lot darker result with portal/indirect. Anyone ?

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some of my edges are quite bright.

Anybody ever run into this issue before?

This is due to the Raytracing Bias (Shading tab). If you reduce it to something like 0.0001 the light leaks should go away. A few other things:

I might change the Color Space to Gamma 2.2.

In most scenes I find that diffuse bounces greater than 3 don't contribute much.

Usually it's best to leave the Min Ray Samples alone. Increasing it I think kind of takes away from the effectiveness of the whole adaptive sampling scheme.

What I'm curious is, how to use portal/indirect lights to get the same result like with environment/indirect pair. I'm getting a lot darker result with portal/indirect. Anyone ?

I created a grid that matches the window and used that for the portal geometry. Greatly reduces the amount of noise.

post-37-0-57416500-1366746476_thumb.png

bright_edges_edit.hip

Edited by DaJuice

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Guest mantragora

I created a grid that matches the window and used that for the portal geometry. Greatly reduces the amount of noise.

Yeah, I know :). I did the same. I know how to setup portal light. Now add to the scene indirect light and render it with Environment On vs Portal On. I'm getting totally different results. Portal/Indirect gets a little brighter but the Environment/Indirect looks like its in full sunlight... just look at the picture.

post-7494-0-13947400-1366750143_thumb.jp

Edited by mantragora

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Ah apologies, I didn't try adding an indirect light. The results from env + indirect are not accurate, but I'm not sure what the cause is.

Edited by DaJuice

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This is due to the Raytracing Bias (Shading tab). If you reduce it to something like 0.0001 the light leaks should go away. A few other things:

I might change the Color Space to Gamma 2.2.

In most scenes I find that diffuse bounces greater than 3 don't contribute much.

Usually it's best to leave the Min Ray Samples alone. Increasing it I think kind of takes away from the effectiveness of the whole adaptive sampling scheme.

Thanks! Very helpful advice

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Today I was trying to set up a simple scene with a hole and an environment light, I'm not sure why but some of my edges are quite bright.

Anybody ever run into this issue before?

Polyextrude your whole box to give it thickness and it will get rid of those bright edges, which is another solution :) . One thing i realised is that mantra doesn't really like non-manifold faces.

Edited by xmetallicx

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After doing mostly other cg stuff for the last couple of months I actually had a little archviz job to do that I decided Houdini would be just right for doing it with. And as I started this thread some time ago I feel obliged to post some work from time to time.

 

The Images are by no means perfect but for a 2 day job nonetheless presentable I think. One day modelbuilding and one day texturing and lighting. Rendertimes where at about 30min per image. All modeled in Houdini, only the piano I did not model myself because of the short time frame. The low poly chairs I did also not model myself. I used them as placeholders and planed to model some myself but the time was a bit short at the end so they stayed.... :)

 

I used portals in the windows, some arealights for the lamps on the ceiling, 2 spots on the stage and some lights for the candles. Minor post with gimp.

 

What you see in the images is a downgraded variant of a so called mirror tent because of hundrets of mirrors that are installed all over the place. In the big version of the tent there are even more mirrors.

 

Cam01_Final.jpg

Cam02_Final.jpg

Cam03_Final.jpg

Edited by count_bobby

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