Creating High Dynamic range images
Posted on Jan 25, 2013

    Creating HDR images

    This post outlines a few different methods for creating HDR images.
    It continues where Part 1 and Part 2 of Image based lighting left off.

    Mirrored Ball Method

    One of there easiest, and least effective ways to make an hdr image, is use "mirrored ball" approach. In this case, photograpsh need to be taken from a single perspective, at 10+ different exposures and merged in Photoshop or HDRshop.

    Surprisingly, when "unwrapped", this provides almost 360 degrees coverage. This approach also shows imperfections in the sphere itself. Note the scratches on the surface metal, the distortion of the surface, not to mention the fact that the photographer and his tripod are in the middle of the picture.

    This is the jpg version of the resulting image in it's original "Mirrored Ball" layout.

    Panoramic Transformations

    Differnt 3D packages expect IBL images in different layouts. Houdini's environment light expects a LatLong layout (also called sphererical mapping). Below is the "unwrapped" version of the image.

    In this case, HDRshop was used to convert the "Mirrored Ball" layout to "LatLong". Artifacts such as the occluded area facing away from the camera, and the photogrphers reflection, were corrected in Photoshop.

    (HDR version Here).

    Wide Angle Lens Method

    Another approach is to use an ultra wide angle lens. Depending on your camera, a 4-10mm lens can provide a nearly 180 degree field of view. With this much coverage, you can capture 360 degrees from 3 perspectives, which are later merged and stitched in Photoshop.

    The trick with this approach is that the 3 perspectives must each be photomerged into their respective hdr images. Then the lens distortion must be removed. Then the three images need to be stitched together. This takes a lot of cloning and image manipulation, but the resulting image is high quality. Compared to the mirrored ball anyways...

    Using a Pano head

    By far the most labor intensive method is to use a panoramic head. This involves taking photos with a standard lens, from 48 perspectives to capture the entire 360 field of view. Keep in mind that you need 10+ exposures of each perspective. Then you need to merge and stitch the results.

    This is for the hardcore, to be sure.

    People using this approach are known to hack their cameras firmware to automate the bracketing of shots. High speed and high capacity memory cards are required to handle the volume of RAW photos.

    The time required to take so many photos usually results in ghosting artifacts: this is caused when objects such swaying trees and grass are in different positions from frame to frame. Lighting conditions can change with a passing cloud etc.
    Usually dedicated software is required to handle the stitching.

    Using a specialized camera

    There is a company called Spheron which produces a specialized camera for just this task. For the ultra high end, this is probably the way to go.

Working With HDR images
Posted on Jan 24, 2013

    What's the problem with jpgs?

    Typical photographs can either display extreme highlights or lowlights, but not both at once. In the example images below, note how the exposure allows either the interior room to be exposed, or the exterior parking lot. This makes them poor choices for use in IBL (image based lighting) and as displacement maps.

    This post is part 2 of a short series on image based lighting. Part 1 here .

    Imitating real-world lighting

    In real life, your eyeball can handle both lighting conditions at the same time. In order to create photo-realistic lighting in CG images however, you need wide range of exposures. In other words, a more dynamic range of lighting.

    HDR images contain multiple exposures and therefore produce better results than their jpeg counterparts. For example luminance values of jpeg can be recorded as values of 0-255 (black to white) vs an HDR which can have ranges of 0-20,000+ (negative black to super white)!

    The photos above were use to create an HDRI for the HDR Path Environment Light asset.

    Can my cell phone can do that?

    Probaby not.
    Not all background images are created equal. To complicate matters, the term HDR has been hijacked by the consumer camera market. Lots of cameras and smartphones can take panoramas. Some will even do so at multiple exposures, combine them, and call this an HDR image....which it isn't. When several exposures are combined like this, and saved as a jpeg, the result is a "tonemap" of an HDR image. Although camera companies are using the term HDR..

    High Dynamic Range Image format

    Standard jpegs have 8-bits of information per channel. HDRs have 16 or 32 bits. So they take up more disk space and are only supported by a few formats such as Radiance (.hdr), Open Exr (.exr). Tiff-16, and Tiff-32 (.tif).
    Very few cameras in the world shoot these natively. Usually one must purchase these images online, or create them in photoshop from multiple exposures.
    When these images are used in a CG rendering context, one needs to be aware that the panorama can come in many different layouts. Just like a map of the world is like an unwrapped sphere, so is a panorama. Commercial HDR images (for rendering) can come in many standard layouts. These correspond to how the image will be applied to a virtual sphere or cube at render time.

    Here are a few examples of environment map layouts:

    Stay tuned for a post on creating your own HDR images!

Image Based Lighting Basics
Posted on Jan 23, 2013

    Image Based Lighting Basics

    It's fairly quick and easy to get photo-realistic results using image-based lighting.
    By using Houdini's built-in tools, or by supplying your own HDR (High-Dynamic Range) image, your renders can inherit a deep, rich color and shadows from real world locations.

    The shelf tool "Environment Light" is a straightforward approach to IBL. Simply create the light and specify an image for it to use. This should be a panoramic image with 360 degrees of view. Also, you'll get much better results if you provide an HDR image (as opposed to a regular jpeg).

    This is what a parorama in Latitude Longitude layout looks like:

    And here is an HDR version of this image to try in Houdini.
    A high res version of this image will be found in an upcoming asset : envLight_HDR_Beach

    Intro to the Environment Light

    Once an image is chosen, the results can be seen immediately.Below is an image which demonstrates some of the various options for the light.

    Portal Geometry

    Another option is to include "Portal Geometry"
    This allows you to mask out part of your environment image so as to simulate outside light coming into a room through a window or open door. In the example below, a simple sphere with a few faces removed illustrates the dramatic effect Portal Geometry can have.

    Once the portal geometry is specified in the light, and "Use portal" check ON. The original geometry can be be hidden. It will still affect the render untill checked off again.

Contest Winners!
Posted on Jan 23, 2013

    Holiday Contest Results

    A few weeks ago we announced a contest to create a holiday-themed image using assets from the Orbolt Smart 3D asset store. Check out some of the finalists here...

    Houdini Apprentice HD licences available to the top finalists!
    So check your email if you entered the contest, cause we're sending you info on how to claim your prizes!

    The contest was open to everybody, and there were several prizes to be won. At the top of our list were users dryulya for the entry "Jazz" (above), and GrosseVieSale for his work "Carte_Blanche" (below).

    Some folks clearly had some fun with this contest. This dancing Santa really caught our attention. Pretty slick moves for a jolly old guy! The author informed us that a customized version of Male Motion Capture asset was used for this render.

    This also shows that one of the benefits of an unlocked asset is that users can really adapt it to suit their needs, or tastes...or sense of humor!

    Kudos to all who your inbox 'cause we have a few runner-up prizes to give out. A hearty thanks to all!

Asset overview movies
Posted on Jan 23, 2013

    Asset overview movies

    If a picture says a thousand words, then a video says 30 000 per second!

    For example, a VIDEO was recently added to the Rocky Ground Asset asset to highlight a new feature. This is an easy way for users to learn about your asset, and any updates you may have added!

Example File Guidelines
Posted on Jan 24, 2013

    Author tip: Example hip files

    What is the best way to show off your work? These guidelines can help...

    It's a topic we've had a bit of time to wrestle with, and after working though a few [hundred] cases, we've put together these guidelines:

    Example files

    What we hope for in an example file is something which..

    Demonstrates key features and value of the asset.
    • Not every feature need be highlighted.
    • Captures the imagination/interest of the user.
    • Demonstrates a literal, practical application.
    • Preferably a production-case scenario of some sort.
    • Shows the asset is a configurable smart asset.
    • Shows different instances of the asset in different configurations.

    You can launch an example file directly from the Asset Browser using the Right mouse Button over the asset.:

    It is a goal of ours to have the user be able to click one asset in the store, and have it open in Houdini looking exactly like its screen shot preview. We really want to avoid the situation where the user downloads and asset, and gets...
    • A blank example file.
    • A file that opens with "incomplete asset definition" errors.
    • Looks quite different from the screen-shot image


    Here are some possible guides to consider.

    When creating an example file...

    The scope of the file should be a single asset.
    • Dependencies are fine, as they are considered part of the single higher level asset.
    • Use of other, non-dependent, assets should be avoided.

    If use of another, non-dependent, asset is necessary for some reason, consider one of these work-arounds:

    Create an artificial dependency.
    • If those non-dependent assets are really necessary, perhaps they should (artificially) become dependants of the asset in question.

    • For example, if tool A's hip file absolutely needs to include tool B, then the author could create an instance of tool B inside tool A, to create an artificial dependency.

More Holiday Submissions
Posted on Dec 21, 2012

    Holiday Challenge Submissions

    Sounds like a wrestling move, looks like peace and goodwill to's a contest!
    We've opened up the forum so that users can now upload images HERE . The Prize for best entry is a 1 year Apprentice HD subscription!

    What are the contest details?
    Simple, just create a holiday themed image using Houdini. Then post the results on the forum .
    Or if you prefer, you can email them directly to

    To make it even easier, we've posted several holiday assets to get you going.

    (full image on the forum)

    Want the file? Feel free to play with this author's Ornaments! Here's the hip file.
    You'll need the Ornament , Pinetree and Screenshot Assets.
    Here are the source images:

    Fabric Colormap
    Fabric Bumpmap

    Here's a preview of one sent in via!

    Keep 'em coming and claim your prize!

Shadow Pass Recipe
Posted on Jan 09, 2013

    Intro to Layers

    Ever notice that CG images tend to have really black shadows? The truth is, %100 black almost never occurs in real life.

    The "Shadow Pass" recipe, mentioned here is good for all compositors. Give it a try next time you're comping a shadow pass.

    Shadow Recipe

    If you were planning on multiplying the shadows at 20% opacity, try 10% instead. Then duplicate the shadow layer and change the apply mode to overlay. On this second shadow pass, apply a levels operation and clip (reduce) the whites by %50. In other words, this overlay layer will have only %50 grey or darker in it.

    That's it! Your shadows will be a rich dark color, but not overly black or muddy.

    Basic composite example

    The following example illustrates how a single CG element was hastily composited onto a photograph. This particular example was done in Photoshop, but the workflow is pretty much the same in Nuke, After Effects or any other package.

    Step 1: Clean-up the image

    The backplate (photo) was taken with an iPhone as the owner went to work. There were some obvious problems with it; Utility lines and hazard pylons just to name a few. These were edited out just to reduce the clutter of the image. Then the levels were adjusted to lighten the forground shadows a little.

    Step 2: Import CG elements

    The goal for this shot was to simply add a big bow to the building. The Giftbox Asset was used to creat a big ribbon around a box shape. A beauty pass and cast shadow pass were rendered.

    Bear in mind, that in a production setting, this "beauty pass" would itself have been a composite of about 10 layers! e.g. Diffuse Color, Specular, Ambient Occlusion, Subsurface, Reflection etc..

    Step 3: Shadows on the building

    This is just a quick exercise, so only one beauty pass, and one cast shadow pass were created. This means that the shadows inside the bow itself will not benefit from the shadow pass recipe. It will only affect the shadows cast upon the building.

    This shadow pass was rendered using a box as a stand-in for the building. This box had a shadowmatte material applied to it.

    Some shadows had to be faked. In this case the shadow of the tree branches had to be added to the bow in order to match the building.

    Step 4: Re-Apply Foreground

    The foreground fence, tree branches and utility pole, needed to be duplicated from the background, and then re-applied over the bow. This was a manual masking or roto task. The edges of this foreground layer needed to be blurred so as to not appear overly sharp and artificial.

    Step 5: Final Composite

    Here is the composited image: A gift wrapped building. Some nice touches would be to adjust the bows color levels a bit, to add a specular pass, and maybe some noise to further sell it's integration with the photograph.
    Happy Holidays!

Putting 'smart' in your Smart 3D Assets
Posted on Dec 21, 2012
    Putting 'smart' in your Smart 3D Assets.. ways to improve your assets

    In this blog we'll dig a little bit deeper and look at what makes a useful asset, and what exactly makes it 'smart'. Houdini digital assets allow the user to take their setup and wrap it into a single node. The author decides which controls will be useful and adds them to the top level. This in itself makes assets a great tool as it lets others use them without having to worry how they work.

    This touches on our first point which is asset purpose and abstraction. When creating a new asset or taking an existing setup and generating one out of it; it's useful to ask ...what is it's purpose?. Having a clear target to shoot for, makes the creation process easier and lets the author be consistent about the functionality. If the task to solve is a complex problem, break it down into smaller/simpler steps and create assets to solve these. Each asset tackles one aspect of the problem and solves it. By having individual components it helps to hide all the gory details that might be needed and abstract it into a simple concepts that a user will understand.

    As you build the asset, keep modularity and flexibility in mind. In terms of modularity the asset should contain all the needed pieces to function. This makes it easier to update later as you only need to edit single asset; instead of multiple ones. It's certainly possible to create an asset that has hundreds of controls and does multitude of jobs but when it comes to either fixing/updating, it becomes significantly more difficult. If it needs additional information try to set clear ways that the asset can get it (whether that's controls for merging additional geos, getting camera/lights/bones info, or writing out geometry to disk).

    It's a good idea to ask yourself which parts of the asset can be made procedural. Doing this during the build phase makes it easier rather than trying to procedurlize it after the fact. It will let you add specific controls and create a robust and flexible asset that has a lot of functionality. One thing to keep in mind is not to go overboard though. Houdini lets you easily add additional options and soon you might find yourself adding everything but the kitchen sink. Try to avoid the temptation :) If there's other piece of functionality that you think would be great to have, see if it's maybe a better candidate for another asset.

    It's the little things.. some additional things to keep in mind as you create your Smart 3D Assets. Grouping your controls by functionality will makes things easier to learn and use by new users. Setting proper defaults/min/max ranges will guide the users and make it easier to know what are acceptable values (if need be you can also lock the controls in Type Properties to place hard limits). Creating asset presets is a great way to show off the asset. One of the best ways to explain and demonstrate your creation is by showing it off with an example hip file. You can upload to Orbolt and the user will be able to learn from it. Describing the controls in the Help section as well as giving tips/tricks is another way to make it more useful (you 'did' write the Help docs.. right? :)

    Keeping the above in mind will help you in creating a great asset, that will be easy to use and allow you to change/update without too much hair pulling. If you have any questions or comments, feel free to contact us at

    Also, have a look at Old Schools digital asset discussions for some great info.
    Old School Blog

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