Simple tutorial for HDRI in C4D

[davesink]

Nice work,Sean!

I've been meaning to get my head around making my own HRDI's.Thanks!

Dave W.

[JIII]

Do you know if Photoshop CS (not CS2) has this feature? The merge feature is what I mean.

Thanks,

-J3

[seco7]

Thanks Sean,

Any ideas on what to use for a good reflective sphere? Is larger better?

[GruvDOne]

Do you know if Photoshop CS (not CS2) has this feature? The merge feature is what I mean.

Thanks,

-J3

It doesn't.. this HDRI feature is new to CS 2. Really though, CS2 only barely has support for 32-bit images. When working with one, 80-90% of PS's features are disabled. It kinda harkens back to a few years ago when 16-bit was the new thing.

CS2's method for creating HDRI's is kinda odd. Basically, you are expected to take several pictures of the same subject with a variety of shutter speeds. Merging the various images together with this new method creates overlapping color data, allowing for for a floating point color manageability.

It seems like it would be much easier to create custom HDRI's for lighting environments with Cinema itself. Since it can output a 32-bit radiance file, and you save yourself a lot time in what is presently a very un-elegant solution, and money in a decent camera ;)

Just my 2 cents

[UK3D]

Hi,
I'm very familiar with Photoshop so it was great news when CS2 allowed me to composite HDR images, even at a fairly basic level. having said that for my use CS2 does just what I need. I shoot 11 images in RAW format then depending on whether they need work or not I select them in Bridge and let merge to HDR do it's magic. I work mostly on a Mac which means I now don't have to shift over to the PC to build the HDRI.

If you are in the UK then Homebase garden section have started selling a good variety of reflective spheres. I bought a large 32" sphere though they sell smaller. Including a 4" which is already on a pole. The larger sphere's have dimpled bases but that doesn't matter as it is a small dimple and can go to the back. Also the circumference weld is detctable if upright but placed exactly on it's side you get a very good, very large reflective sphere. The size really helps in getting a good distance from it when shooting, especially if you have a decent lengthy lens. Inside I use a 23-70mm outside I use a 70-400mm.

I'll be refining this technique over the next few weeks and I'm happy to hare any tips.
Ta sean

[nycL45]

Thanks for posting Sean. I am definitely interested. A question though: do you have a process for earlier PS versions?

[NWoolridge]

Do you know if Photoshop CS (not CS2) has this feature? The merge feature is what I mean.

Thanks,

-J3

Photoshop CS doesn't, but the free apps HDR Shop (on the PC) and Photosphere (on the Mac) will allow you to create HDR files from a bracketed series of photos:

http://gl.ict.usc.edu/HDRShop/

http://www.anyhere.com/

CS2's method for creating HDRI's is kinda odd. Basically, you are expected to take several pictures of the same subject with a variety of shutter speeds. Merging the various images together with this new method creates overlapping color data, allowing for for a floating point color manageability.

This is the whole point of the original HDR format, to create "light probes" of real environments (see http://debevec.org/). Its only latterly that 3d apps light cinema have been able to themselves generate high dynamic range output. Usually, the lovely complexity and irregularity of real-world light probes, and the reflections and lighting effects they generate, are what people are looking for when they use HDR images. Creating that real-world complexity in a 3d app would take quite a bit of time, and makes taking a few photos and spending 10 minutes in photoshop much more attractive! :-)

Nick

[UK3D]

Hi,
Nick is right. The whole point for me is to speed up my lighting process and at the same time give a more life like rendering. It's great that 3D applications can generate HDR images but the project I'm looking at combines two of my loves/skills. Going out and photographing some lovely real locations and then capturing the lighting conditions using the reflective sphere and finally placing a 3D character/object in the photograph knowing the lighting will be accurate.
Today was both a success and a blow out. I managed to capture one locaction. However the subsequent locations were far too windy. Couldn't get my sphere to stand still. I'm now contemplating drilling holes in it's base so I can fix it to a tripod.... or something. At one point I was literally chasing the sphere down a hill.. not what I had intended.

Ta sean

[JIII]

On that note, do you have any advice for the actual physical set up, angle of shot etc.? I have always wondered how you actually take a photo of an globe, without making yourself too prominent in it, and photohraphing the areas that you want. i.e. the top of it for the entire area etc.

Thanks,

-J3

[TonyL]

The mirrored globe/sphere business seems like an awful lot of trouble to me.

With the ability of some (admittedly higher-end) cameras to bracket exposures, it would seem to take only a few seconds to generate enough different exposure levels to give you the frame-count for a HDRI. 7 different exposures are enough to give a reasonable HDRI.

There is another way though, but this requires PS CS2. Create a document with a 2:1 aspect ratio (i.e. twice as wide as high). Fill the bottom third with black. Fill the top two-thirds with a gradient (say, light blue to dark blue, with the dark blue at the top). Flatten the document. Change the bit level to 16 bits (under Mode). Then change the bit level to 32 bits (again under Mode). (You can't go straight from 8 bits to 32 bits!) Save as Radiance. Voila!

OK, this does not give the variation in dark and light tones that a true HDRI shows, but there is no reason why you could not brush in clouds, etc.

This was described in a recent issue of MacUser, so I claim no credit for it. Hope it's helpful to someone.

TL

[UK3D]

Today's test.
http://www.uk3d.com/other/riverside.jpg
The image above is the sort of thing I’m creating. Obviously the objects are just to test the lighting is working, which it is. The idea is to get a good composite of 3D object in a photographed background with accurate lighting. The sort of thing we see in commercials the whole time these days.

To answer Tony first. Yes yes there are many ways of creating HDRI and I’m sure some easier ways of faking environments. However for me I’m going to be shooting locations, using a probe to capture the lighting conditions then creating 3D characters to be composted in the photographs. This seems to be a relatively quick way. I’ve yet to experiment with fish-eye lenses or extreme wide angle lens but will be giving those a go too. Meanwhile I’m happy with the sphere results both inside and out.

To answer John. There are a couple of approaches for minimising the photographer in the image. The first use a large sphere and a long lens. I used a 70mm in the image above but use a 400mm when conditions are right. You have to be very careful of wobble on the bigger lens’s. The second is a bit mad, use your timer on your camera and dash behind the sphere and lay down. You’ll be cropping the background out so as long as you are not caught in the 360 degree you’ll be fine.. ha. You’ll still have the tripod and camera there though.
Some people go the length of masking themselves out later which is a lot of work. I’d say wear something black and keep low. For me it’s not a problem as I’m mostly using the HDRI for the lighting condition, any reflections will be very indistinct.

I really must find a way to secure my sphere now. Any suggestions? Ta Sean

The tutorial link http://www.uk3d.com/other/hdri_in_c4d.htm

[seco7]

Sean, can you just use a photographers beanbag to hold the sphere? Or two, one on top and one on the bottom? Or weight the sphere from the inside? If you are shooting on soft surfaces, maybe you can use a long spike of sorts to push into the ground?

How did you stage the HDRI in the latest example (which looks great btw)? Two domes ala Maxon example?
Steve

[UK3D]

Hi Steve,
Yes two sphere's one for the Illumination and one for the reflections. In my examples I have made the reflection sphere invisible to the camera but not reflections. This means I can drop a background image in and render on top of that. This will help with my final positioning.

Bean bags are a good idea but in a grassy area I need the sphere to sit a little higher than the ground. Inside I can use a wide necked glass. Outside i tried a plastic cup... but the wind was against this idea.. I did think of driving a spike through the plastic cup fixing it to the ground but I reckon the wind would still have shifted it.
I think something more drastic like you suggest, a spike through the sphere or maybe a hole big enough to attach a clamp, which in turn is attached to a tripod... hmmm

Ta Sean

[TonyL]

Hi UK3D,

Yes, your way is going to be a lot better; I can see that. I would be very interested to see the results, and look forward to you posting some examples. I might even have a go myself with this technique.

Best wishes - TL

[JIII]

Hmm, but how do you get 360 degrees with just one shot of a ball, I mean it seems to me that the max you can get is 180, unless you are photographing the TOP of it, which would be insane.

-J3

[JIII]

For instance, like photographing the entire skyline and sky, that would take a shot from the top wouldn't it?

-J3

[UK3D]

Hi JIII,

What I meant by 360 degree was 180 horizontal bye 180 vertical. Not sure what that is supposed to be? A half sphere anyhow, not a full sphere. Is 180 degrees for both horizontal and vertical? I can't remember now....

I have to say picking the right day to shoot on is goin to play a big part. Today the sun was in and out every few minutes playing havoc with the lighting range. Really need a 5-10 minute window of consistent sunlight. Which in the UK is not going to be easy...

Now back to drilling that reflective ball...

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