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Hard Disk Shredding

One of my holiday projects was to streamline my storage needs.  The recent floods in Thailand have affected global hard disks (HDD) supply.  The 3TB drive I bought four months ago for $129 goes for more than $300 now, and the shortage / high price period is likely to continue throughout 2012  as supply catches up with the shortfall. Hence the need to be even more careful than in normal times.

If you are building a new PC now, I strongly recommend a solid state drive (SDD) instead of an HDD for the system drive.  60GB SSDs sell nowadays below the current price for the lowest cost HDD of $100 and 60GB is more than sufficient capacity for the system drive of most users. Even the least of the SDDs outperforms HDDs by a magnitude of factors. Larger capacity HDDs are still critical for the storage of large quantity of data such as photo, audio and video, but this data need not be stored on the system drive.  I will try to stretch my existing storage capacity until the shortage is over and prices are back to normal.

HDDs have a limited life span.  The question is not whether an HDD will fail, but when.  The secret for data preservation has been known to the monks in the monasteries of Europe long before the introduction of Gutenberg’s press: replicate, replicate replicate.  RAID is an automated, modern incarnation of the monk’s painstaking manual process of replicating books to preserve their content in time.

While most HDDs come with a three years warranty, and some are even warranted for five years, the warranty is a false sense of security.  It does not cover the stored data and is only indicative of the expected useful lifetime of the device before data is lost due to a failure.  Most failures don’t result immediately in data loss, but the recovery becomes prohibitively expensive. On my desk I keep a 120 GB HDD that is more than ten years old and still working despite intense 24/7 usage during many years and a transatlantic move.  But I have also had HDDs that failed after less than a year.  If this happens in a RAID, it is not critical.

My strategy is to use only fresh HDDs for critical data; to store such data redundantly; and to replicate it to fresher / newer HDDs within a maximum of three years.  After their first job in the RAID is over, I re-purpose older HDD for non-critical purposes such as scratch or cache disks, but at some point they fail and the question is what to do with the waste. I bring old electronics to the municipal recycling station, but I take the HDDs out of them before doing so.  The abounding stories of sensitive data being retrieved from the HDDs of second hand PCs sold on eBays makes me reluctant.

Disassembling an HDD is not a difficult task. All you need are a couple of torx screwdrivers.  This was the occasion for a little bit of son-dad quality time.  My son was fascinated by using a real screwdriver rather than his toys.  He learned about magnetism from the two magnetic blocks of the drive’s actuator and he was fascinated by the mirror polish of the platters. Now all the parts can go to the recycling station, except the platters themselves which I will take care of rendering unreadable.

Brackets

Critical for the successful panorama shooting workflow is the bracket between the camera and the base rotator. It’s function is to align the position of the lens’ no-parallax point (NPP) to the rotation axis of the rotator. This overview will help you select the bracket that is right for you.

Bracket-Types

Flexible vs. Single-Purpose

Flexible brackets are adjustable to fit many camera/lens combinations. They require careful calibration and could accidentally get uncalibrated during transport or shooting.

Single-purpose brackets don’t need adjustment. They are ready to work out of the box with the specific camera/lens combination for which they were designed. But they become obsolete when the camera/lens is changed.

For versatility, go flexible. For speed and simplicity, go single-purpose.

Single-Row vs. Multi-Row

Single-row brackets like my heavily modified Agnos MrotatorCP are simpler to set up and operate. They positions the NPP vertically above the axis of rotation. For web-quality, including full screen spherical panoramas, single-row with a fisheye lens is good enough.

Multi-row brackets like the Nodal Ninja 5 or MrotatorU have an additional rotator, usually smaller, with an axis of rotation perpendicular to the first axis of rotation. The bracket positions the NPP at the intersection of the two axes. For higher resolution and better quality multi-row with a lens narrower than a fisheye is a good choice.

Brackets and Rotators compared

Brackets and Rotators compared

Benefits To Look For

Precision

The precision of a panorama head (and thus of a bracket) is paramount. There is a lot of misconception about what precision exactly is and what it is for. The critical feature you don’t want to miss is the ability of the bracket to align precisely and consistently the lens’ NPP with the physical axis of rotation of the pano head. Look for sturdiness. Any straying away from the NPP is paid for with a difficult stitch often requiring hours of manual retouching.

The misconception is that precision equals repeatabilty; that after a full 360° turn the camera is still millimetrically positioned in the same place, looking in the exact same direction. This is supposed to be critical for batch-stitching – the ability to stitch, unattended, a large batch of panoramas taken with the same setup. This is not true. Modern software, including hugin (with Bruno Postle’s Perl Panotools-Scripts) and proprietary Autopano Pro will crunch through batches of panoramas without the constraint of repeatability.

Form Factor 1: Mobility

Panoramas shooting often involves moving the equipment to the location of the photo shoot.  The weight and volume occupied by the pano head in the luggage does make a difference. This is the reason why I set out to modify the original Agnos MrotatorCP. The bracket was a heavy and bulky piece of steel which I redesigned in lightweight aluminum that makes the overall pano head sturdier, lighter and smaller. The Manfrotto 303 QTVR might be one of the first and most versatile designs, but I would not want to lug it around.

Form Factor 2: Camera/Lens

Some of the lower-end brackets are not large enough to accommodate the larger, professional cameras and their heavy lenses. Check the manufacturer’s compatibility list, or even better, get to your local reseller and see how sturdy the bracket is with your camera/lens combination.

Tools

Particularly for those brackets that require calibration, having the tool to do that is always handy. Even better: brackets that do not require any particular tool, e.g. the PinnacleVR I tested last year. It can be calibrated with a coin and the calibration is millimetrically precise and guaranteed to stick. If your setup require tools, make sure they are always in your bag.

Operability

A properly calibrated panorama bracket should be as easy to operate as in turn, click, repeat. Even the completely newbie to panorama that knows how to press the button on the camera should be able to simply move the camera to the next position and push the button. If the turn, click, repeat cylce is too difficult, it may also eat away from the time of the seasoned professional. When shooting you want to deal with the scene, not with the gear.

Other Features

There are plenty of other features that might or might not be relevant to you, depending on the shooting conditions (metal is very conducive to heat and in cold temperature uncomfortable to handle compared to carbon fiber, PVC, or other composite materials. There are great pano heads made out of wood. If you shoot pole panoramas, you want to have locking mechanisms. And you don’t need to have deep pockets to afford a motorized pano head. The designs on the market have made a lot of progress in the past few years, and while panorama making (and particularly full spherical panoramas) is still a niche speciality, there is a growing industry catering for our needs.

Now that Christmas Shopping is over, you may find some interesting Boxing Day deals!

Footprint

A critical characteristic of a base rotator to shoot full spherical panoramas is its footprint – the smaller the better – because it is this footprint that requires nadir editing. I am the lucky owner of four rotators:

  • The first rotator I ever bought (after using a self-constructed one for a while) was a Manfrotto’s 300N.
  • I bought and modified an Agnos MrotatorCP in 2005 to easily produce full spherical panoramas in a single row shooting.
  • I received a pre-production Agnos MrotatorU, courtesy of our Google Summer of Code 2007 sponsor. The base rotator is an improvement (the compass is engraved) over the same design I bought in 2005.
  • I received a Fanotec Nodal Ninja 5, courtesy of our Google Summer of Code 2008 sponsor.

Below are their footprints compared._mg_6381_2_rotators

Footprint alone is not everything: the higher the distance of the camera from the base, the smaller the footprint.

The rotators belong to different classes.

The Manfrotto is a very flexible rotator with many options. It has steppings up to 5°, while the competing Fanotec and Agnos models do not get below 7.5° and 18° respectively. It has a lock knob; the stepping can be set by simply placing the stepping knob in the appropriate thread. A unique feature is the decoupling of the top plate, to position precisely the starting angle for the shooting sequence.

The Nodal Ninja rotator is a compromize between features and portability. It is thin and lightweight, but changing stepping require opening the rotator and using a tool to replace the detent ring. Nodal Ninja users who want more flexibility will upgrade to an R12 rotator. Nodal Ninja has the best finish and detail of them all – there are additional holes for anti-twist pins to keep the bracket steady, and underneath, not visible in the pictures, is an exta thread next to the tripod thread to keep the 3/8″ to 1/4″ adapter safe if it is not used.

The Agnos rotator is a single purpose, no-maintenance rotator and as such nothing can go wrong and it is fast and easy to operate. Agnos users who want more flexibility will upgrade to a RotatorT.

All of these rotators are precise enough to be batch stitched with the appropriate software – the relevant precision is not the (impossible) exact repeatability of positions, but the exact rotation around a single point. Until I received the Nodal Ninja, I used the 300N for flexibility, e.g. when shooting gigapixel panoramas. Abd the Mrotator for ultra-fast single-row full spherical.  I will likely set up the Nodal Ninja for something in between, or maybe replace the modified Agnos if I can get an add-on to the Nodal Ninja to keep the camera slanted.

Smart Packaging

Almost no environmental waste, and the packaging material is at the same time a very practical case. This is all there was in the paper envelope, and how my Nodal Ninja 5 arrived. Don’t even bother to save the few bucks on the not packaged version – you’ll do yourself and the environment a disfavor.

Smart Packaging

Smart Packaging

November

November was a busy month – busy with things that are not ripe for public talk yet. The snow has covered the ground here, and in the coming weeks I will have time to unpack my Nodal Ninja 5. Stay tuned.

Nodal Ninja Sponsors Hugin/Panotools team that participates in the Google Summer of Code

Nodal Ninja in actionAlthough software advances have made it less critical than it used to be, proper alignment of the camera on the No-Parallax Point is still the single most important factor to succeed in the shooting of a stitched panorama. There are many solutions to keep the camera in the right orientation, commercial and home-made.

Most students who will contribute code to Hugin this year in the context of the Google Summer of Code don’t have such specialized pano gear. Isn’t this unfair? They give software away to the general public, and can’t use it to its fullest potential because of the lack of appropriate hardware?

Last year, Agnos stepped in and graciously offered an MrotatorU panoramic head to each successful student and his mentors. This year, the Nodal Ninja comes to the rescue! We are a vendor neutral-endeavor and we are proud to count another industry leader amongst our supporters. The animated image in this post shows a Nodal Ninja 3 MkII in action, courtesy of Bill Bailey, Director Global Sales and Marketing.

Bill is known as a contributor to the panorama community, even though he is now so absorbed by his duty to Nodal Ninja customers he hardly has time to shoot panoramas. Many photographers appreciate his practical approach. The camera settings publicly available from the Nodal Ninja website are useful also for owners of competing brands. Bill and his business partner Nick Fan, founder of Fanotec, have made efforts to coordinate and collaborate with the community on the settings data base.

In the short time we have been negotiating this deal, Bill surprised me positively a few times. I felt almost uncomfortable at so much generosity:

  • He added free EZ-Levelers to the already generous package;
  • He offered to donate a Nodal Ninja 3 MkII package also to those mentor registered with our organization who have no students assigned this year;
  • He showed a real understanding for Free Software and its synergy with hardware manufacturers. Hugin will soon be distributed with each new Nodal Ninja;
  • And the deal is not completely closed yet – Bill’s proverbial customer service is such, that he cares about his customers (and he makes us feel like customers, even though he is the one footing the bill) in every detail – he has offered T-adaptors for those who have cameras that need one.

With sponsorship from both Nodal Ninja and Google Hugin is set for another exciting summer.

Displays

Display technology is making giant strides. Thinner, bigger, higher resolution, better color and contrast. And better value for money too. Inspired by Ted Gould’s blog’s entry, here a few thoughts about the consequences for panorama making and usability.

1. The Human Eye

The human eye has an average angular resolution of about 0.02°-0.03°. If we were surrounded by a circular display we could theoretically distinguish 18,000 pixels on a horizontal line. The pixel size would depend on the circumference of the line. If that circumference had a radius of 60cm/2ft (typical desktop display distance) the corresponding pixel pitch would be 0.2mm or 122 pixel per inch. At 30cm/1ft (typical notebook display distance) it would be 0.1mm or 244 ppi.

Since 98% of the audience does not zoom on panoramas, 18,000 pixels is enough horizontal resolution for a full spherical panorama in most cases.

2. Aspect Ratio

The absolute dominance of the 4:3 aspect ratio, inherited from last century’s TV, is over. TV is finally switching to 16:9. Unlike ten years ago, this time it’s real.

5:4, introduced for high end displays in the CRT era, has a spike of popularity as the native resolution of the early 17″ and 19″ LCD display. It will be superseded by 16:10.

Widescreen is here to stay, but is not alone. Ultramobile PC (UMPC) and cell phones add variety, for example the 4:3 QVGA of Nokia’s N95 and Apple’s iPhone.

Last but not least, dual displays: below an example of 2×19″, with a combined aspect ratio of 10:4.

photoshop ubuntu thumb

We can no longer assume a specific aspect ratio, and this influences the choice of initial zoom.

3. Display Resolution of the future

1024×768 and 1280×1024 are still dominant, but their share is falling rapidly. Conventional wisdom is that a 6000 pixels wide equirectangular is enough for a full screen panorama on a 1024×768 display.

HDTV and Blu Ray Disks are setting a new standard. 1920×1080 pixels is here to stay in the living room. Discerning media consumers that want to protect their investment will not settle for less. That’s 1920×1200 on the desktop and these displays have recently reached a pricing sweet spot. I expect their market share to grow dramatically. To satisfy the quality of such display, at least 12000 pixels wide equirectangular are recommended.

But the distribution is becoming wider. In the past ten years more than 80% of displays were between 800 and 1280 pixels wide. Now the distribution is stretched upwards by Full HD and downwards by UMPCs with 1024×600 and 800×480; and the cell phones with 480×320. And somewhere in between are notebooks; 1280×800 is currently the most popular notebook display resolution.

We must cater down sampled versions for those displays.

4. Size

At least one things stays constant: Panoramas are better viewed full screen on large displays.

Optimal display size depends primarily on user preference and on the application. There is no one-size-fits-all solution. For the living room,even at 60″+ bigger is still better. For cell phones and UMPC the opposite is true. For desktops there is a comfortable compromise between size and viewing distance; and for notebooks the main trade off is mobility.

There is a fixed relationship between the field of view of the eye, the viewing distance and optimal display size. At about 10cm/4″ a display of 14″ will cover more than what the eye can see. On the laps, at 30cm/1ft, it will be equivalent to a 62″ panel in an average living room setting.

5. Controls

The different sizes and display resolutions have a consequence on control: they change size. What may looks right on an UMPC is a microscopic stamp on a Full HD display and what looks right on the Full HD display covers so much precious screen real estate that the actual content being controlled is hopelessly hidden. Adjust control size to display size and give the user an easy way to switch between the different control sizes.

6. Conclusions

To keep up with the evolution in display technology:

  • upgrade to a camera kit that can produce equirectangulars of 12000 to 18000 px width
  • adapt initial zoom to detected aspect ratio
  • adapt resolution to screen size
  • adapt controls size to display resolution and let the user override the adjustment
  • keep displaying panoramas in full screen
  • one-size-fits-all no longer works

RAID

All hard disks will fail. Backup strategies have been devised to avoid data loss with the inevitable hard disk failure. This article is not a comprehensive backup strategy. It explains the concept of RAID and how it can fit in a backup strategy.

R stands for redundancy. The only backup strategy that works. Copy. Rinse. Repeat.

R stands for replication. In the days of analog recording, an expensive process resulting in degraded quality. Digital copies are cheap and lossless.

RAID is a redundant array of individual disks. It automates the replication process. A safe haven for data when used properly. Beware of a false sense of safety.

Levels

There are a few different types (levels) of RAID. The most popular are:

  • RAID 1, known as mirror, keeps two disks in sync.
  • RAID 5 distributes data across many disks and uses one for a check sum.
  • RAID 0 is not a real RAID: there is no redundancy

Storage Capacity and Speed

50% of the total storage capacity is usable with RAID 1, because data is kept in two copies. With four disks, RAID 5 achieves better efficiency (75%). RAID generally increases speed by distributing load. RAID 5 and 0 are faster than RAID 1.

Modern RAID controllers come mostly with 4, 8 or 16 channels. This is the number of drives that can be attached. Some cards can be synchronized within a twin card for double the channels. Get the card with more channels if you can afford it.

Failure Resilience

The main reason to adopt RAID is to prevent the consequences of hardware failure. Both RAID 1 and RAID 5 are resilient to the failure of a single disk. If more than one disk fails chances are that the data is gone. RAID 0 is not failure resistant. The probability of two disks failing at the same time is close to zero. Buying two disks from two separate production batches helps decreasing that probability further.

The advantage of RAID 1 is that most of them are compatible with standard controllers. In case of controller failure, connect a disk to a standard controller for immediate data access. Back up!

If the RAID 5 controller fails, the data is no longer accessible until a controller with same algorithm is installed. Finding a replacement can be difficult.

Hardware RAID vs. software RAID

RAID is fully automatic and transparent to the user. It requires some processing during both read and write. Purely hardware driven RAID controllers tend to be more expensive because they have their own processor and RAM.

Cheaper controllers are equally effective in terms of storage safety, but use the CPU and RAM resource of the host computer. This can be a potential bottleneck if the RAID is hosted on the workstation.

The controllers linked above are more than adequate for individual or small team use. I’ve installed them in many locations. More expensive and advanced RAID cards are available, amongst other from Adaptec and 3ware. I use an Adaptec SCSI RAID controller for a mission critical database server.

In the past few years many motherboards started offering on board RAID. I don’t think much of them. First and foremost because a motherboard failure may also make the whole RAID useless. Then also because those things tend to be reduced versions of the real things, like on board video and sound.

Where to host the RAID ?

The RAID can be hosted inside a workstation or on a network server. With today’s giga ethernet, the speed penalty of accessing files over the network instead of directly is negligible for most applications. The dedicated server solution makes the impact of a software RAID less critical. Most important: good ventilation of the disks to increase their longevity.

Monitoring RAID

RAID is easy to set up and gives the impression that it is fire and forget. It is not. The management utility that come with professional RAID cards helps monitoring the health of the arrays. The RocketRAID family has a useful web based management tool. It can set up regular tasks (such as weekly overnight verification) and email alerts. Then it is really fire and forget.

Comprehensive Backup Strategy

RAID is online storage. It immunizes data against the failure of a single hard drive. It does not immunize data against system malfunctions: if the system overwrites it, it’s gone. Offline Backup is the solution for that. It also does not immunize data against location-failures, such as physical theft or fire. Off-Site backup is the solution for that. I will discuss comprehensive backup strategies in a future article.