Better colour accuracy. All my HDRi skies were shot with a Canon 1dsmk3 so I like to keep as much as possible of that information preserved in the HDRi file. Radiance (.hdr) is limited to sRGB colour data, whereas OpenEXR (.exr) is not.
This is reflected in the file sizes:
For this skydome for example
the exr file size is 160mb, the hdr version is 50mb
That said, I have decided to start including a .hdr version in the products I am selling on 3docean. I’m still updating all the files, but check back soon and if you have bought one of them you can re-download a new version for free.
Why hdr? Unfortunately some applications don’t support exr, so until they do you can use hdr (albeit in the knowledge that your colours might not be quite as lovely*)
The Phoenix Flowers is a new public realm intervention by 7N Architects in Glasgow, Scotland. I worked on the 3d visualisations in September last year and was very interested to see photos of the completed project by my ex-colleague and friend Dave Morris.
At the time I remember being happy with my work but not completely sure how ‘real’ the images looked. As it turns out, the red carpet and flowers are even more intensely coloured in reality! Take a look at the full set of Dave’s photos here, below are a selection for comparison. When I saw Dave’s photos I felt I had to go back and render a couple of extra views, so the 2 below were done to try and match his compositions.
render:
photo:
render:
photo:
For me, the interesting things to notice were the relative intensities of the highlights (how the Canon 5D dealt with them compared to vray), the colour of the lighting behind the grilles (goes towards yellow in reality despite being red) and that I was pretty lucky in getting the flower petal material looking about right.
Not a new technique, you can find good tutorials by Bertand Benoit and Philippe Steels here and here, but it remains the best way to create displacement maps for repetitive things like roof tiles, metal panels and in this case expanded metal mesh. The great thing about doing a material like this with displacement rather than a straight opacity map is that it looks different depending on the viewing angle, which adds to the realism.
I made a quick model of expanded metal that looks something like this:
then did a quick top-down render and saved the zdepth element as a 16 bit png. Its important to save as 16 bit if you want a nice clean and smooth displacement, 8 bit often doesnt have enough grey levels so you get a stepped gradient which looks ugly when displaced.
This is what the finished displacement map looks like:
Exterior renders of Allandale House by William O’Brien Jr. who is Assistant Professor of Architecture at MIT School of Architecture and Planning as well as running his own design practice.
I’m planning a making-of tutorial, but first I wanted to show some high res versions of the exteriors (interiors to follow) as they really should be viewed big for best effect! The following renders are my particular favourites of the exterior set, click for a high res version.
Occasionally its nice to be able to use a HDRi environment together with a vraysun, for when you want stronger shadows than the HDRi supplies. The trick is in aligning the sun with the HDRi so that the shadows from each match up. You can do this through trial and error, but if you want to change the rotation of the HDRi then its a pain. Rather than try to explain the steps involved, I thought it would be quicker doing a video tutorial. I’m afraid it turned out to be 13 mins long, but hopefully it will help.
This is my complete collection of 54 HDRi skies, the ones already available to buy on 3DOcean are marked with a red logo (you can click through to 3DOcean.net). Feel free to let me know in the comments which ones you think would be useful to you. If you hover over the thumbs you should get the name of the HDRi, and if you click you’ll get a 1000px preview.
Thought I should do a quick tutorial on how I use these HDRi Skydomes I’m selling. Note that this is just one of many possible workflows, and there are probably lots of tricks I’m missing and even things I do completely wrong. I should also say that I work mostly with still images, not animations.
1. Here is a typical architectural scene. It is a model I made of Waro Kishi’s Fukaya house in Japan that never really went anywhere.
2. I use a gamma 2.2 workflow together with reinhard color mapping, so not strictly LWF but shares some of the advantages. I don’t want this to turn into a LWF tutorial or discussion, but this post on cgpov.com pretty much sums up how I feel a gamma corrected workflow helps us as visualisation artists.
The reinhard color mapping helps to control burnt out (overexposed) areas. Screenshot of my color mapping set up: The burn value of the reinhard color mapping typically ranges from .75 for an exterior to 0.05 for an interior. You need to experiment with the value until you gain control over the burnt out areas. Here is an example with a camera pointing at the HDR sky:
For the final render, I use the Vray Frame Buffer, and add a slight s-curve to the output to compensate for the lack of contrast that the gamma corrected workflow introduces:
3. Add a vray dome light and load the exr/hdr using the max bitmap loader. Set the mapping type to environment/spherical. If you are using .hdr files, you can use the vrayHDRi loader instead. It makes no difference whether you use the bitmap loader or the vrayHDRi loader, the vrayHDRi adds a bit more control in that you can control the render multiplier independently from the viewport multplier. Set the output of the .exr to 1 and the vraylight multiplier to 1. If your hdr/exr has no alpha channel it seems you can save quite a bit of memory while rendering (approx 200mb in my case) if you load the exr/hdr as realpixel float rgb rather than the rgba option.
[Click for original size]
4. To rotate the HDR you need to enter a U offset value from 0-1, so to rotate 180 degrees with would enter 0.5, 270 degrees 0.75 etc.
5. Add a vrayphysicalcamera, and set the aperture and shutter speed to something that would work for a typical outdoor scene, like F4, 1/200th & ISO 100. Remember that you are in effect using a completely manual camera, there is no ‘P’ or automatic mode so you need to experiment with different exposures until you get a good result.
[Click for original size]
6. Hit render and see what you get. If it looks too dark/bright I tend to adjust the bitmap’s output rather than the vraylight multiplier, so that I can have a couple of ready setup HDRi’s ready to drag and drop onto the dome light. In the examples below I use an output value of 1.5.
The first HDRi skydome is available on 3docean. It’s a clear blue sky with just a few clouds. I’m hoping to be able to offer packs at a discounted price as well, but that’s dependent on 3docean, so for now it’s just going to be individually. Feel free to let me know what type of skies you would like to see next, the image below is just a selection from many!
UPDATE: The slideshow below will automatically update as I add new HDRi skies.
