Post process

Deleting the tripod

To do this we need a program like Photoshop. You will need 32-bit HDR support and layer capabilities when using other software. I will explain this with Photoshop. A little warning first: when using full-resolution (10.000px) HDR images and layer them over each other it will eat your RAM like cheddar cheese! Approx. 1 GB per layer is needed. when we need the base layer, and two extra layers for the tripod images, it makes some 3 GB. With 4 GB of RAM you will feel the brakes kicking in here... 6 would be the minimum, but I would recommend using 8 GB or more.

  • So, now we open up the folder where PTGui saved the stitched result and the single warped layers. the stitched HDR will have its filename ending with "_HDR.hdr", the other layers we need will end with "_layer_9.hdr" and "_layer_10.hdr" open these three files in Photoshop.
  • We have to restore down the main HDR window now, so we can drag and drop the other HDR layers in this window.

 

  • Now open up the Layers window, by clicking "Window - Layers" or by pressing "F7" select one of the HDR files containing the warped tripod. drag and drop this layer from the layer window onto the stitched HDR window like below.

 

  • Repeat this step with the other tripod file, so we now have the main HDR file, with the two tripod layers over them.
  • Next step is to apply a Layer Mask to both of the added layers. click "Layer - Layer Mask - Hide All" and you will see a black square pops up in the Layers window next to the Layers Thumbnail. this indicates the layer mask is active. Shift-clicking the Mask Thumbnail disables it, and Alt-clicking it displays only the mask and hides everything else.

 

  • Now the point of this layer mask is as easy as brilliant: Black Mask color hides the underlying layer, white color shows the underlaying layer. these layer masks are in greyscale, so you can paint nice transitions between two layers, and that's exactly what we will do to hide the ugly tripod.
  • Select the top tripod layer, and Shift-click on the Mask Thumb to disable it, and check witch side is clear, and witch side holds the tripod, Shift-click again to enable the Mask. Now select a white brush the size about double the thickness of the tripods leg. make sure the hardness is 0% (right-click the brush in the image), and just start to paint out the tripod on the clear side of your active layer.

 

  • Do the same with the other layer, and you will have the tripod worked out of the stitched HDR image. The only thing that's left now, are 2 darker areas at the top of where the tripods used to be, left by the stitching software and a bit of overlapping shadows, will be dealt with in a minute. First merge the three layers together. Right-click on the background layer and select "Merge Layers"

 

  • Now if you don't have HDR thumbnail support in your explorer, you will have to open up PTGui again to find out what layer to use. I prefer it this way actually, so I can see clearly witch image overlaps the part I want to edit. Click the small "Edit Individual Layers" button at the top left (highlighted in red square) to see the individual layers and mouseover to find the correct ones. in this case it is layer 6 and layer 2. Close PTGui.

 

Now if you are running at 50% RAM or more, I strongly recommend you to restart Photoshop. somehow the merged layers are still kept in the RAM. so if you are going to open 2 more layers, you will approach some limits here. After opening the 2 extra layers, my RAM counter is close to 10 GB!  

  • So after the restart, we open up the merged HDR we edited before and the HDR layers 6 and 2. The removal of the two darker areas is done the exact same way as we removed the tripod layers. import the layers over the stitched HDR, apply a Hide All Layer Mask to both layers, and draw the darker areas out.
  • The small piece of overlapping shadow at the outer left and right of the HDR image is just drawn away with the clone stamp: Hit "S" and Alt-click near the shadow spot to sample the stamp, now draw over the shadow spot to hide it. do the same on the other side.

 

Pretty much done now... I will leave the misaligned telephone cable for yourself to play with. You could open the sky layer and warp it into place, just be careful that the line stays straight, witch means it should have a fluid curve in our HDR image!

 

Preparation for 3D use

If we want to use the image in 3D software, we have some small adjustments to make. Depending on the size of the render you want to make of it, you won't need an image as large as this one. it will surely affect the rendering time. So I like to make some different sizes, to suit different rendering needs. and off course the lightmap needs to be very small and blurred to prevent a noisy render.

  • Click on Image - Image Size to open the image size dialog window. Enter your desired value for the size of the map. I usually make a 5000, 2500, 1000 and 500 pixels wide image, where I can use the 500 pixels wide image as the lightmap.

 

  • The lightmap only needs to be blurred when the size is correct, click on "Filter - Blur - Gaussian Blur" to open the Gaussian Blur window, and enter a Radius value of 7 pixels.

 

Congrats! you have successfully created a 360 degree HDR image! go get yourself a cup of tea or coffee, you've earned it!

 

Tone mapping the HDR panorama

If you want to use the HDR panorama in a 3D application, you are done. But you could make an artistic tone-mapped version just for fun, I will briefly tell you how to do this with Photomatix and Photoshop. Photomatix is great for artistic, colorful and contrast-rich tone-mapping, while Photoshop is great for more realistic tone-mapping.

  • Open the HDR panorama in Photomatix and click "Process - Tone Mapping" or press Ctrl-T. You have can tone map using 2 methods: the Details Enhancer and the Tone Compressor for the most radical results, use the Detail Enhancer, for more realistic results, use the Tone Compressor. When the result is satisfying, click process and you can save it as a JPG or BMP for normal viewing on a standard monitor. I have to say, this image is not the best to reveal Photomatix's power, but you will get the idea.

 

  • In Photoshop (CS4) the possibilities are not as extended as in Photomatix, but if you want to create a realistic looking LDR this is your best choice. Just open the HDR and click "Image – Mode – 8 Bits/Channel". In the popup screen choose "Local Adaptation" from the pull-down menu, and open the extended parameters. It works just like the normal curve in Photoshop. If you make a smooth S- shaped curve to get some more contrast, you will most probably get a pretty result, maybe tweak the curve a bit to enhance details. What you do to the curve is entirely dependant of the effect you want to create, and a matter of personal taste. Just go ahead and play with it. When you click OK you can save as a LDR JPG or BMP.

 

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