HDR: Evening Sun

GiantCowFilms posted this on Tuesday, December 1st 2015 at roughly 3 o'clock in the afternoon

This image was tone mapped for previewing. view the non-tone mapped preview here

Specifications:
• Licence: Creative Commons 0/Public Domain
• Dynamic Range: 20.46 Stops
• Original Size: 29184 x 14592 – Uploaded at 12.5% original resolution
• Camera: Canon EOS 70D
• Lens: Canon 18-135 STM
• Set EV: +13.988 @ 100 ISO – You can adjust the exposure after the fact if you need
• Coverage: 360 x 180
• Date Taken: 11/29/2015 2:43 – 2:59 PM
• Location: Northern United States

This sun-capturing HDR has a full 360×180 range, and stores the light found in the early evening. In this one the color of the sun was tuned for best results.

Lessons Learnt

The sun in this one was a little desaturated, and I think it was due to lack of sufficient ND filters. I need to go down about 2-3 stops. The problem is, at around this point, IR light starts to flood the sensor, and ND IR filters are quite pricey, so for now I will tweak the color of the sun in post. It may seem “inaccurate” but as long as the desired light, colors and reflections are achieved, no harm has been done.

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HDR: Direct Sun

GiantCowFilms posted this on Friday, November 27th 2015 at roughly 4 o'clock in the afternoon

Specifications:
• Licence: Creative Commons 0/Public Domain
• Dynamic Range: 21.07 Stops
• Camera: Canon EOS 70D
• Lens: Canon 18-135 STM
• Set EV: +13.99 @ 100 ISO – You can adjust the exposure after the fact if you need
• Coverage: 360 x 180
• Date Taken: 11/26/2015 11:26 – 11:41 AM
• Location: Northern United States

This HDR has a full 360×180 range, and captures the light near mid day (the sun is still angled since it is winter, and the location is fairly far north).

Lessons Learnt

Trying a new bracket merge algorithm, seems to work better, but still room for improvement, especially regarding ghosting. Again this image suffers from ICE image stitch errors, which seem to be particularly bad across brackets, as if ICE changes the stitch for different brackets, even though it shouldn’t be.

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HDR: Breaking Dawn – Frosty Morning

GiantCowFilms posted this on Tuesday, November 24th 2015 at roughly 2 o'clock in the afternoon

Specifications:
• Licence: Creative Commons 0/Public Domain
• Dynamic Range: 6.06 Stops
• Camera: Canon EOS 70D
• Lens: Canon 18-135 STM
• Set EV: +10.32 @ 100 ISO – You can adjust the exposure after the fact if you need
• Coverage: 360 x 180
• Date Taken: 11/22/2015 7:58 – 8:06 AM
• Location: Northern United States

This HDR has a full 360×180 range, and captures the beautiful light visible in the early morning, creating stunning renders. This HDR was taken while waiting for the sun to rise above th trees for my Winter Sun – Morning HDR.

Lessons Learnt

I’m investigating ICE, which I use to stitch the panos, as it seems to be causing ghosting, I thought my tripod head was loose the first few times, but this time I made a POINT of keeping it solidly locked into position, and I am still seeing strange inconsistencies between the stitched brackets. I think I might give the Hugin pano-stitcher another shot as I have quite a few complaints with ICE.

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HDR Instructions

GiantCowFilms posted this on Monday, November 23rd 2015 at roughly 3 o'clock in the afternoon

I post free HDRs on this site. This is a quick usage guide demonstrating the techniques required to get optimal results.

HDR images work best using the cycles render, as the Internal Render Engine doesn’t render these correctly. To add an HDR in cycles, first head into the node editor, and use material mode, and select the world texture. Second check use nodes:

Third add an Environment Texture (ShiftA>Environment Texture) and connect it to the input of the background node (a background and output node should appear when Use Nodes is checked. If not, add them using the ShiftA menu.

Fourth the HDR is added to the scene, by clicking the open button on the environment texture node, and selecting the correct downloaded .HDR file.

Finally, to massively improve render performance, check multiple importance sample in the world properties, under settings. The map resolution may need to be increased for higher resolution HDRs.

The HDR should now be working, give it a test render.

Setting Exposure

I make an effort to choose a good exposure for every HDR that I post; despite this effort, the exposure won’t always look right, depending on the scene. Adjusting the exposure of an HDR is easy, It is even possible to closely match the exposure of a camera.

To set a new EV for an HDR, it is first necessary to determine the difference in EV between the current HDR’s brightness, and the target EV. The EV of every HDR on this site is posted under Specifications, under “Set EV”The next step is to subtract the target EV from the current EV, and then apply that EV to the image.

Here is the node setup for applying EV:

The image is the incoming input on the top, and the EV is the bottom.

An EV can be derived from camera settings, using the formula

$EV = \log_2(\frac{N^2}{t})$

Here is a blend file containing a cycles node implementation of the formula in addition to some other EV tools:

It is not necessary to set an EV, the exposure/brightness of a scene can be set simply by adjusting by eye, using the add or subtract node. There is no correct brightness, it is entirely a subjective thing, exactly like setting the exposure on a camera. The big difference here is we are changing the brightness of the lights and not the camera, 3D is slightly backwards like that, from a cinematography standpoint.

CUDA Error

A common issue with using HDRs is running out of GPU memory when running in GPU mode. When this happens the render will quit and this error will be given:

CUDA error: Out of memory in cuArrayCreate(\$handle, &desc)

This error occurs when the HDR is to big to fit into the memory of a particular graphics card. There are two solutions:

• Buy a better graphics card
• Make the HDR smaller

Making an HDR smaller is not as easy as it seems. A lot of software that “claims” to handle HDR files may actually have difficult with the extremely high values found in some HDRs that include the sun. The best option for scaling the image is blender.

In blender, switch into composting mode in the node editor and check Use Nodes

Delete all the default nodes, and add four nodes, using the Shiftmenu:

• Image Texture
• Scale
• Crop
• File Output

The reason I choose File Output over Composite is to avoid having to set the dimensions of the render. After linking the images up, select the HDR that is going to be edited using the open option on the image node.

After linking the nodes, set the values of the scale and crop nodes to match those in the image. They are currently set to scae the image to 50% size. In a large number of cases, 25% scale may work better.

The first scale node cuts the size in half and then the crop node cuts of the black borders the scale node leaves behind (25% off each side). Be sure to set both nodes to relative, and check Crop Image Size on the crop node. The output node saves the image, be sure to set it up accordingly, so that it saves the correct file type: Radiance HDR (You can also convert to .exr if you like).

To scale to 25% size, the values for the nodes should be, left to right top to bottom:

• Scale:
• X: 0.25
• Y: 0.25
• Crop:
• Left: 0.375
• Right: 0.625
• Up: 0.625
• Down: 0.375

For calculating the node values for other scale factors, the formulas are

Left and down:

(1 – [Scale Factor])/2

Right and up:

(1 – [Scale Factor])/2 + [Scale Factor].

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HDR: Winter Sun – Morning

GiantCowFilms posted this on at roughly 1 o'clock in the afternoon

Specifications:
• Licence: Creative Commons 0/Public Domain
• Dynamic Range: 22.38 Stops
• Camera: Canon EOS 70D
• Lens: Canon 18-135 STM
• Set EV: +12.14 @ 100 ISO – You can adjust the exposure after the fact if you need
• Coverage: 360 x 168.1
• Date Taken: 11/22/2015 7:58 – 8:06 AM
• Location: Northern United States

This HDR captures the full dynamic range of the sun. It has a few weak points in the stitching and merging; however, it is still quite useful for most purposes.

I was inspired to create this HDR by Greg Zaal’s Mpumalanga Veld HDR which also captures the full brightness of the sun. Most of my workflow is based on the one Greg Zaal shared.

Lessons Learnt

Keep a checklist of camera settings, I accidentally left auto white balance on, and had to correct it (Hurrah! for raw files)

Here is a quick checklist:

• Card In Camera
• No Lens Cap
• White Balance
• Media Format (turn raw on)
• Manual Exposure
• Brackets Correct
• shutter and f-stop
• Any Filters?
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HDR and Textures FAQ

GiantCowFilms posted this on at roughly 1 o'clock in the afternoon

Q: Why are you doing this?

I’m doing this for fun and in the hope that someone might find these useful. I often get things done thanks to free resources, and I would like to do my part.

Q: Can I share these on my website?

Yes, you can, but please link here – its not required, but It would mean a lot. You can even bundles these with commercial products.

Q: Why don’t you charge money?

I got 50 times my money back by using other people’s free assets.

Q: Are your HDRs as good as commercial HDRs?

These are better and worse then some. HDRs that capture the full dynamic range are quite rare, and therefore in that light these are exceptional, however they do also have their flaws. I could and would have spent more money on gear for shooting a commercial product, and they would have been better; however, these are by no means low quality.

Q: These were exactly what I needed for my project, is there anything I can do to support you?

You can make and share quality assets under CC0/Public Domain licenses. If you send me the link, I may, if they are good, post a back link.

Q: Can I get a higher resolution copy of one of your HDRs

Please contact me, specifying the output dimensions you want (if they are too big I will send you the fullsize) I will send you a temporary download link. Sadly due to space limitations I cannot keep large file copies on the server indefinitely.

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