Tuesday, March 27, 2012

Panorama View from Home Workstation

I sidetracked from my 3D work (again) and started playing with photography. The initial aim was to create a spherical panoramic HDR image of my work and play space at home, in other words, my computer desk. The purpose of the HDR image is to simulate image-based lighting for my 3D projects. While I was stitching my HDR image, I came across various software applications and ended up with this unexpectedly.

Pretty cool eh? Sound is muted by default. Toggle the mute button and face the monitor to hear directional background music from the computer.

I don't remember what the video playing on the monitor screen is about. I just randomly grabbed it from my collection of vids and inserted it into the panorama flash. ^^;;;

The other reason for making this panorama project is to show off my very plain looking apartment and today marks the first anniversary since I moved here. That reminds me I have another 29 years left to repay the bank housing loan... doh!

Check out the floor plan of my apartment I designed before moving in. Not much has changed since I planned the arrangement of the furniture and fittings.

Anyway, let's get back to the topic on photography. I am currently shooting with a Sony Cyber-shot digital camera, the DSC-HX9V, which I bought a few months ago in November 2011. I purchased this high-zoom compact camera because "It's a Sony!!!".

Sony Cyber-shot DSC-HX9V

Nah, just kidding! I chose it due to its widely acclaimed reviews for shooting beautiful HD videos. You could say I am more geared towards shooting moving pictures than still images and being a cheapskate, I am reluctant to fork out the money to get an expensive camcorder.

So far, I've taken over 10 hours worth of video clips with it and I would say the video quality is pretty satisfactory. Other than the thirty minutes limit for each video shoot regardless of storage capacity, I don't have any complaints in the movie making department of Sony DSC-HX9V.

Sorry I won't be sharing those video clips with the public since they are mainly for family viewing only. Maybe I will think of something else to shoot and upload it to YouTube later.

As for shooting still images, my sister said they turn out too red. Fortunately (or unfortunately depending on your view), I can't really tell the difference. I didn't manage to take as many still photos until recently when I messed with this HDR panorama thingie. I spent quite some time researching photography stuff like EVs, F-stops, ISOs, white balance and what not before I could get started.

Image taken from Crazy Magazine.

To make a panoramic image, I have to rotate the camera slightly between shots and then combine or stitch the photographs together. Unlike professional digital SLR cameras with fisheye lenses, my digital camera has only a 24mm lens, meaning I need to take many shots in small rotations to complete a 360 degree panoramic image.

The Sony DSC-HX9V has an intelligent panorama sweep mode which I feel is meant as a fun feature for casual photographers. I will not be able to get consistent results for every sweep. Moreover, I cannot shoot in different exposures required for HDRI under this mode.

Illustration from PSDtuts+.

To make a full spherical panorama (360° x 180°), I repeat the same camera rotation process with a slightly pitched angle until I reach (near) the zenith and nadir.

Illustration from KOLOR's wiki pages.

Because I'm a noob photographer, I actually had to redo the shooting session of my workstation at least three times over a few weeks. I could only do it at specific time on Sunday mornings when everyone in the family is still sleeping so as to minimize movement and ghosting effects in the final HDR output.

An example of ghosting effect in HDR photography courtesy of HardwareZone.com.sg.

In every shooting session, I believe I took approximately 800 to 900 pictures of my desk's surroundings. I prefer redundancy than worry about missing parts later when I stitch my spherical panorama together.

My first try was a disaster. I took my pictures handheld and they were all rendered useless due to prominent parallax issues. The Sony DSC-HX9V camera can only take three continuous shots in auto-bracket mode. If I want five different exposures, I will have to shoot one area, change some settings on the camera, and shoot the same area a second time. All these unnecessary movements and poor understanding of the nodal point resulted in alignment anomalies.

Parallax problem along edge of the desk.

Slowly but surely, I made progress in subsequent photography sessions. I modified a mini tripod so that the camera rests just slightly above the desk but not too high. This way, I can adjust camera settings without displacing the position of the camera too much. I also devised a method to rotate the camera around its nodal point to minimize parallax errors without the aid of a panohead.

Modified tripod for more stability.

When I finally thought I have a good set of images, I didn't realize I screwed up the exposure of each individual shot when I used the Program mode on Sony DSC-HX9V. Little did I know, the EV settings in the Program mode will not control the shutter speed manually. Instead, the camera will automatically calculate aperture and shutter speed values to ensure proper exposure for every scene before applying my EV settings.

Panorama shot in Program mode.

Notice the strange lighting around the monitor without any post processing. In Program mode, the camera tries to compensate for areas that are too bright or dark. This image would have been acceptable if I want something stylish however I am looking for a more realistic look.

To remedy this problem, I had to re-shoot everything by specifying the exact shutter speed in Manual mode instead of using the EV presets in Program mode. Shutter speed is set to 1/20 of a second for the first bracket and 1/80 of a second for the next. Each bracket produces 2 more photos that halves and doubles the stated exposure time, resulting in a range of exposures that represents -2EV to +2EV in 1 EV increments.

Here, you can see the complete set of successive exposures I took to make the final HDR image.

The manual settings used on the camera are as follow.
  • ISO 400 (I sacrificed a little quality so that I could use relatively fast shutter speed to prevent blurring without the use of a controller or timer.)
  • F-stop: f/3.3 (My other selectable aperture size, f/8, makes the image too dark for this scene.)
  • Manual Focus: Infinity
  • White Balance: One Push Set (An option to pick the brightest area manually with the Sony DSC-HX9V.)
  • White Balance Shift: Off
  • Color Mode: Real
All other settings set to "Standard" or the default value.

When taking photos at the highest resolution with my camera, I can create a full spherical panorama with actual pixel dimension of 21112 x 10556. My computer has only 4GB of RAM and I have no choice but to reduce the size to something more reasonable, i.e. 8000 x 4000, in order work with it efficiently.

Note: When downsizing a 360 degree panoramic image, remember to use bilinear scaling if this option is available in your photo editing program or else you may find a seam at the edge of your panorama when you wrap it around to form a sphere!

Vertical seam seen in Panotour Pro's 3D editor view.

Throughout this entire exercise, I've experimented on many different software to stitch spherical panoramas and merge HDR images. Having said that, the list of software applications below shows the ones I favored due to their simplicity of use and the end results they produce.
  • Photoshop CS5 (For aligning different exposure shots and touch up prior to HDR merging.)
  • PTGui Pro (For stitching shots together to make the full spherical panorama.)
  • Photomatix Pro (For compiling the bracketed photos to output the 32-bit HDR image.)
  • Panotour Pro (For creation of panorama flash.)

Photoshop can actually do a surprisingly good job on aligning and merging panoramic images using the Auto-align Layers and Auto-blend Layers functions. However, be prepared to reserve huge amount of scratch disk space when working with big stacks of layers. On the contrary, PTGui Pro requires less memory space and seems to merge photos much faster than Photoshop in my case.

Auto-align Layers and Auto-blend Layers in Photoshop works really well.

The most interesting software I find here is probably Photomatix Pro. I am not very good at tone mapping or exposure fusing photos but I'll showcase some of Photomatix's fancy presets with my own HDR image.

For more information on HDRI and spherical panoramic photography, check out this useful site http://www.hdrlabs.com/tutorials/.

To conclude this lengthy post, I can say this is my most challenging photography experience up-to-date. I doubt I will be doing something similar again unless I have better equipment at my disposal other than a compact digital camera for casual use.

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