ArchVis HDRI Tutorial

7/22/2019 ArchVis HDRI Tutorial

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Architectural Visualization with HDRI Skies and

V-Ray

by Paco Morales


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Arch Vis with HDRI and V-Ray

In this tutorial, we will illumi-nate an exterior architecturalscene with help from V-Rayand a HDR image (High Dy-

namic Range Image, or HDRIfor short) from HyperfocalDesign.

Using 3dsmax and HDRI Skieswith the V-Ray renderingengine will enable us to createsuper realistic results. OurHDR sky image will be usedto light our scene and to cre-ate realistic reections with ahigh level of realism, and withgreat ease of use. Conven-

tional light rigging schemescan eventually achieve similarresults, but with lots of timewasted on experimenting andtweaking. And time is money.

We will use the V-Ray render-ing engine, adjusting severalparameters along the way toobtain nice shadows, materi-als, caustics, etc. V-Ray hasproved itself to be a marketleader for speed, ease of use

and stunning lighting capabili-ties.

The rst thing we will do isdownload the necessary lesto start building and settingup the scene, and provideit with lighting and materialinformation

This is a step by step tutorial,with lots of images to helpgrasp the general workowidea. After all, one good im-age is better that a thousandwords!

You can nd the 3d le at-tached with this document.

For the sky, if you do not

have one of Hyperfocals HDRISkies you can of course useone their free HDRI sam-ples, which can be found in

http://www.hyperfocaldesign.com/free-textures/

You could use a sphericalHDRI for your scene, how-ever you will usually nd youhave unwanted objects suchas buildings or trees whichdo not match your scene.You may also get unwantedlighting, color and reectioninformation.

We will use one HDR image inseveral different sizes - onesmall image for the illumina-tion and larger ones for thebackground and reections.Note: This is not always thecase, do some tests beforecommitting an HDRI for abackground. Depending onyour scene, you may havelittle in the way of reec-tions, and you may not needa dynamic HDRI background.

In this case just resample theHDRI Sky to 8bit at the expo-sure level of your choice.

The resolution of the HDRI forthe background and reectionmapping is larger than that ofthe lighting image. For light-ing we just need to get thegeneral intensity, color anddirection of the illuminationfrom the image, whereas forthe reections, we need lotsof detail showing. The higherthe detail, the more realism in

our nal render.

INTRODUCTION

Scanline render, standard lights

HDRI Sky + V-Ray

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LIGHTING SETUP


I like to handle the large background/environment HDRI inde-pendently, as this way you can adjust the background expo-sure level to suit your taste, without affecting the reectionsor lighting.

In other words, you can make the sky HDRI look brighter ordarker without over or underexposing the scene, this is good,

as you have more overall control over the scene this way. Thisis effectively a way of tonemapping within your scene.

Lighting HDRI

Reection HDRI

Setup your white and blackpoint as shown below, butdont clamp the HDRI, oth-erwise you will lose the valu-able illumination information.Clamping the sun may reducesplotching and specklingartifacts in your nal render,however you are better off re-sizing or blurring your lightingHDRI. You will need to adjustthe RGB level to match your

white point gures.

First disable Default Lighting under Global Settings and de-lete any lights you have in the scene.

Now we load the HDRIs into the material editor; one for theillumination, one for the reections, and the other for the En-vironment. Follow the instructions for the lighting HDRI belowand then setup your reection and environment HDRIs in the

same fashion.

Shortcut Key F10

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We create a direct light with the values shown in the imageshown to the right.

You can follow the images to see where I have placed the light.But it really is a matter of taste, and of course, it depends onthe particular scene.

Press (Alt+B) and a win-dow will appear (Viewportbackground). Use thevalues as shown on thescreengrab.Then adjust the direct lightas per the image above,

because we need to matchthe direct light with thesun position within theHDRI.

DIRECT LIGHT SETUP

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SHADOWS


Here is the image with the direct light, this provides strongbut dispersed shadows.

In the images shown to the right, different values havebeen applied to the V-Ray shadows with resulting levels ofshadow sharpness.

The rst image has a value of zero (0 with 32 subdivi-sions), giving it a focused look with no fading. In thesecond we have a value of 1 (1 with 32 subdivisions), andthere is now some fading in the shadow borders. And so ontill 4 with subdivisions. I personally use a value of 3.0 with32 subdivisions most of the time.

UVW 0.0 (32 Subdivisions)





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EXPOSURE


Here we have the image with pure illumtion provided by the HDRI, without direclight and the resulting soft shadows. Depending on what size lighting HDRI you and whether you blur it or not, you will that you can achieve anything from veryblurry shadows to quite sharp. Howeverlarger your lighting HDRI, the longer yorender times and the harder it will be toremove speckling/splotching artifacts.

Depending on the scene and the look wwish to achieve, we can work with or wiout direct lights. For example in this clo

sky image, the sun is behind the cloudsgiving a soft shadow look. Many of the HSkies in the Hyperfocal range have the spositioned on a cloud edge, allowing theartist to choose a direct light/hard edgeshadow appearance, or a soft shadow apearance as if the sun is behind the clou

With a single sky you can alter the exposure level to cre-ate a number of different looks or atmospheres, as youcan see in the images below. Or view the animationhere.

Multiplier 0.1 Multiplier 0.25 Multiplier 0.5 Multiplier 1

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http://www.youtube.com/watch?v=JpeNtrAAjEMhttp://www.youtube.com/watch?v=JpeNtrAAjEM


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For the materials, you can use the screen shots of the ma-terial editor below as reference.

Glass

In the reections of the submaterial, weput a falloff (fresnel), this will make a mo

realistic-looking material. Just dont overdit.

With fresnel, and without fresnel

Water

MATERIALS

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Floor

Apply a grey scale bitmap toroughen up your reection map

Chrome

White/Building



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RENDERING AND GI

Shortcut Hot key F10

If you want caustics,make a plane with150 segments eachside, and collapseto a mesh. Thenadd some noise, asroughness is needed

to make subtle variations in the surface,and this generatesthe caustics.

You can see the set-tings above.

Note:Remember to enablegamma correction inpreference settings.Go to Customize >

Preferences > Gam-ma > Enable Gammacorrection.My values are 1.8



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Final result, HDRI + V-Ray with Caustics

CONCLUSION

I hope you enjoyed this tutorial. If you haveany queries or suggestions then please mailme at [email protected]

Visit my Blog

http://paco-morales.blogspot.com/

For more HDRI related tutorials, articles, newsand products, visit www.hyperfocaldesign.com

mailto:[email protected]://paco-morales.blogspot.com/http://www.hyperfocaldesign.com/http://www.hyperfocaldesign.com/http://paco-morales.blogspot.com/mailto:[email protected]


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About the author

Paco Morales lives in Mexico and works as a freelancearchitectural and still life illustrator and animator.

Paco discovered the fascinating world of 3D in univer-sity, and it was there that he started to learn simpleprograms like Minicad and Autocad. When he nisheduniversity he enrolled in an Autodesk Training Centerin Mexico City and since then has studied Illumina-tion, GI, modeling and HDRI.

Paco is a winner of numerous awards and challengesand has also written a number of tutorials includingthis one.

http://paco-morales.blogspot.com/



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ArchVis HDRI Tutorial