WP's SloMo

SpeedCam

Digital high-speed camera concepts

Existing analogue high-speed film cameras still have their rights in the field of high frame rates of several 10 000 frames/sec. Even if the state of the art digital video systems have already broken through the 1 000 000 frames/sec barrier. The resolution in this region, however, is very strictly limited then. Nevertheless, already there are sensors with about 1 000 x 1 000 pixel at 5 000 frames/sec Full HD 1080p or with more than 2 500 frames/sec and more than 500 000 frames/sec or even more than 1 million frames/sec at reduced resolution are possible. As a rule of thumb one can say that at maximum frequency the resolution at least decreases proportional to that at standard frequency - 10 times faster with at at least 10 times reduced resolution.

But digitization rules! The roots of digital high-speed camera systems go back to the early 1980s or even before them. Their resolutions, however, were rather low - some ten by ten pixels at some hundred frames per second.

Legend to the figure on the right: RAM = image memory; µC = microcontroller or processor; A/D = analogue to digital conversion (often already integrated in the sensor)
The green card should show a PC card, the red line connection possibilities (image and control data).
The standard connection can be e.g. (Gigabit) Ethernet or FireWire.

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Overview

System description

A selection of digital high-speed cameras, ancient company Weinberger 1993 to 2008

Each SpeedCam appliance, here chosen as typical example and due to being familiar to them, was a member of a family of fully digital PC based electronic (video) high-speed camera systems of the ancient company Weinberger. They were designed as turnkey systems like most high-speed cameras. Consisting of a camera (head), software and depending on type with control device/host PC. Here just a not complete comparison of different system generations as some kind of gallery of forefathers in order to show what is possible and how it has been done.

More info about other systems and manufacturers you can find also in the [SloMo Links] section of this site.

Comparing the systems one recognizes the development to significant better resolutions with moderately increasing frame rates. A »Triple-K-Camera« (1 000 x 1 000 pixels per square at 1 000 frames/sec) meets the entry level demands of today's high-end »mainstream« market. With resolutions in the megapixel class the image quality of high-speed film cameras is reached making it possible to replace this technology in great scale.

By the way: these digital high-speed cameras were often used by professionals as digital normal speed video cameras (25 or 30 frames/sec and 50 or 60 frames/sec, resp.) for making movies/videos. Their image quality was everything one could wish for and they were possibly cheaper than usual video cameras for professional broadcasting use. And all speeds were possible - 25, 30, 50 or 60 frames/sec, even 24 frames/sec as used for cinema movies.

Technical data

Each resolution is given by columns x lines. Specs without guarantee.

Technical data of the SpeedCam high-speed cameras

SpeedCam 500+/2000+ systems came to market in the early 1990s. In the middle of the 1990s complemented by SpeedCam Lite and SpeedCam 512.
With the SpeedCam PRO including LT (single channel variant) and G plus (crash-proofed control host) starting in the end 1990s one could choose between color and monochrome camera versions. Even the mixed operation at the same host was possible.
With SpeedCam Visario (Generation 1) the new millennium was inaugurated. The reference class in 2001/02. Now even cameras of different memory capacity could operate in parallel. 2004/05 SpeedCam Visario g2 (Generation 2) continued the development to the stand-alone and crash-proofed camera. In 2007 SpeedCam Visario g3 (Generation 3) again pushed the landmarks sensitivity, dynamic and frame rate in a considerable manner.
Well, even in those days a great stuff was possible. (And they continue to work more than Ten Years After ;-)

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Correlation between frame rate, recording capacity and resolution

Relationship image and memory [SloMo Image RAM]

Each SpeedCam system uses the full resolution of its sensor just slightly above nominal frame rate (see the table above) to offer some reserve for re-synchronization during external synchronization and especially during clock jitter. All resolution steps show this behavior. Even with maximum frequency.
With increasing frame rates two, three and finally four lines or columns, resp., of the CCD sensors are combined step by step and are read out (binning). The field of view remains the same, but the quality of the images decreases. With heavy reduction they may show then some kind of beam structure or graded etches. The table above shows the dependence of maximum resolution on maximum frame rate.
Concerning the SpeedCam Visario CMOS sensor, however, the resolution (i.e. quality) remains the same, but the field of view changes, see the figure on the right and for details click [SloMo Image RAM].

Of course, one cannot speak of quality in usual terms concerning the harsh resolution reduction binning modes, but the spreading of a crack or of a wave front can be visualized. As experience shows halving the resolution does not cause a significant loss of quality. Besides one can just rotate the camera head by 90° to get the high resolution in the preference direction of the movement.

The required illumination does not increase due to the combining of lines/columns when binning and remains nearly the same, so a SpeedCam PRO system does not need more light for 3 000 frames/sec with a resolution of 128 x 512 pixels than for 1 000 frames/sec with 512 x 512 pixels.
With binning-less SpeedCam Visario time of exposure is just a matter of shutter time or frame rate, resp. only.

The recording time depends on the resulting data amount. The memory extension is the stable part, the rest is flexible more or less. The following formula shows the general connection (with 8 bit = 1 byte; 1 kbyte = 1024 byte). It is valid for all digital video cameras in general.

Memory extension [byte] =

To calculate with these high-speed camera systems listed in the table above e.g. 1 Gbyte, the maximum memory extension of SpeedCam PRO, is sufficient enough for 1 Gbyte / (512 x 512 x 1 byte x 1 000/sec) = 4 seconds. For 2 000 frames/sec it covers 4 seconds as well, because the column number is halved.
SpeedCam Visario and other up to date cameras, however, operate at a color depth per channel of 10 bit or 12 bit. Here the color depth factor is then 10/8 = 1.2 [byte/pixel] or respectively 12/8 = 1.5 [byte/pixel].

Of course, one can voluntary reduce the frame rate and/or resolution. A memory extension of 1 Gbyte lasts e.g. for 16 seconds with 250 frames/sec at 512 x 512 pixels or for 32 seconds with the same frequency, but at 256 x 512 pixels.
By the way: as undocumented feature many of high-speed camera systems offer more or less limited support of the so-called wobbling (also named sweep). When one puts a moderate changing frequency to the SYNC IN socket, it will be continuously taken as present recording frequency. This may be interesting for shooting ramp up sets like the start up of a motor.

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System configuration

Two worlds side by side: PC plus camera

The configurations of SpeedCam +500/+2000 and SpeedCam 512 systems are are based on a 19 inch industrial PC with passive ISA bus board as it was state of the art in the early 1990s when they have been developed. Due to the separation of PC and camera section possibly up to three channels per host are available, because the camera section has its own communication channels. So e.g. to support fast replay video data can be stored back from the harddisk to the memory banks on the frame grabber. In general the system configuration matches the figure below. Operating system is MS-DOS on Intel 80486 processors.

SpeedCam lite is lacking of the host PC section and the possibilities associated with it. But it is designed for (extreme) field use - easy to handle and easy to carry and it even offers built in rechargeable battery (accumulator ) and monitor.

Two worlds combined: camera system with PC

SpeedCam PRO data and control paths

For the control unit of the SpeedCam PRO (and LT, G plus) system a switch to an industrial 19 inch rack with CompactPCI bus as it has become common in the mid 1990s has taken place. For data- and control paths and for peripherals to connect, too, see the figure on the left. (Of course, PC standard ports like LPT, COM ... are supported.)
Possibly up to four channels per host are available.

The generated data rate of up to 256 Mbyte/sec per channel cannot be transferred to the computer section in real time, because a PCI based bus offers a theoretic capacity of maximum 132 Mbyte/sec (33 MHz with 32 bit bandwidth) only. Therefore the image data of each channel are spooled to DRAM benches on the according ADMEM (= A/D conversion + memory) card and later they are written through the MONCON (= monitor + control) card to the harddisk of the host PC. All image data, even those already stored on the harddisk, can be replayed any times on the host PC and on the TV monitor or can be sent to a video recorder, resp.

SpeedCam PRO systems can be remote controlled by Ethernet and run on Intel Pentium or Celeron CPUs under Windows 95.

The at first sight obsolete concept nevertheless claims its position even nowadays by allowing to keep the camera head comparatively small, light-weight and simple.
If one separates the real camera control from the computer, one will get two devices, and one will just have to connect the computer (e.g. a notebook) for parameter setting and download of data only, while during the test the control unit is keeping the system in operation. For the use of multi-head systems onboard crash test vehicles with their restricted weight loads and spaces an advantage not to underestimate.
Other manufacturers continue to use this setup as well. It is common sight in industrial image processing.

Entire and network high-speed camera systems

Star topology with host and hubs

High-speed camera SpeedCam Visario g1 data and control paths

The SpeedCam Visario g1 system is a representative of the forward-looking conception on the way to the intelligent stand-alone camera. But still the intelligence of the system is not located in the camera head itself. It, however, differs from the previously described systems: the A/D conversion and memory are integrated in the camera head. Thus according to the memory extension up to eight Gbyte data are buffered in it. And the according PCI bus card is called MULTICON due to its capability of driving up to 20 cameras, four directly and four each with up to four Linkboxes, in real time. Theses devices, especially the MULTICON, take over the real control part inside the system.

One basic advantage of Visario is the single cable solution with data transmission in real-time: WideLink and LocalLink cables carry control, synchronization and trigger signals and the latter even offer the power over wire function. Therefore the blue and yellow control cables are just optional.
Please take notice of the propagation direction of the control signals. There is no way back for them from the camera to the Linkbox or the host PC. There exists a path from the host PC to the Linkbox and further on to the camera only.
The Linkbox can substitute the host PC occasionally. The Linkbox and its cameras can operate in stand alone mode, i.e. without connection to the host PC. The crash-proofed Linkbox offers PAL or NTSC live images for adjusting jobs, e.g. covering the setup in order to prepare a crash test vehicle. Like systems with central control unit of other manufacturers, too, this concept is especially useful for multi-channel systems in complex and/or widely spread test setups.

The distance between host PC and Linksplitter can be extended to some 100 m using a fiber optic transmitter device. The Linkbox can be remote controlled by cable or by radio. A crash-proofed battery back-up device is available optionally as stand-alone or as set-top box for each camera offering operation without external power supply.
(By the way: with SpeedCam Visario the use of push-pull connectors has gotten popular in digital high-speed camera sector worldwide.)

One can integrate Visario in an Ethernet network and especially using the Corba software interface it can be remote controlled. Operating system is Windows 2000 or XP on common PCI/AGP motherboards depending on size in a 19 inch industrial PC or as Mini-ATX in easy portable version.

High-end camera, partly autonomous with host

Cine SpeedCam function blocks

Optimized for the use in TV broadcast and movie business the Cine SpeedCam system is based on the Visario architecture with a modified and revised Visario camera core and a special sensor selection. Of course, the image quality requirements for a camera system used in movie and advertising business are really extraordinary. The least feature is the completely pixel-fault free sensor. The Cine SpeedCam marks a break-through for digital high-speed cameras in HDTV and movie making use and was internationally awarded in broadcast market - NAB2004, USA, Las Vegas.
For filming work-flow the camera head offers an additional real-time PAL or NTSC viewfinder and extended visualization, trigger and power feed possibilities.
The Visario roots allow the use of the standard equipment of the device family inclusive Linkbox despite its complete different design and entire black finish.

The host in the Cine SpeedCam rack is equipped with additional real-time high definition video cards and with fast buffer SCSI harddisks providing a short time to render and to replay the sequence on HDTV level.

There is also a Cine SpeedCam Mark II or »Cine g2«, a thoroughly selected, reworked and upgraded SpeedCam Visario g2 with superior image quality.

Stand-alone intelligent high-speed camcorder

SpeedCam Visario g2 function blocks

The variation of an all-in-one self-contained high-speed camera is marked by SpeedCam Visario g2. Here PC and control interfaces (I/O like trigger, synchronization and IRIG-B time code) are integrated in a crash-proofed camera head together with the further improved Visario camera core. In simple words and with advertising appeal expression it configures a real high-speed camcorder, even if one will appreciate to use a notebook for camera control. Because due to roughness reasons there is no user panel integrated. Visario g2, however, can provide a live image at the camera directly.
The basic connection is provided by standard Gigabit Ethernet (100/1000Base-TX) to a PC or a LAN. Its built in operating system is Embedded Linux.
Cascading optional crash-proofed control devices (Crashunit, Crashswitch) allow controlling and power supply of local Visario g2 groups and of selected cameras of other manufacturers in spread test setups. There are third party manufacturers for this kind of power and signal hubs apart from the camera manufacturers as well.
In easy terms a table-top power supply and a notebook with an Internet browser are sufficient to operate the camera. A Java camera utility for basic functions is already installed in the camera.

Integration of a harddisk, of a flash disk, of a video output (NTSC or PAL) or of a fiber optic interface (1000Base-FX) is possible.
An additional integrated crash-proofed rechargeable battery (inclusive recharging electronics) enabling complete camera operation for up to two hours is available.

Mixed operation of different SpeedCam Visario cameras at the same control host or in the LAN is possible. Supported by a common software interface those of other manufacturers can be integrated, too. This is in respect to the set-up of extended test sites. The operating system for the host PC or the notebook is Windows 2000 or XP.

High-end stand-alone high-speed camcorder

High-speed camera SpeedCam Visario g3

Functionally built up alike and even designed in a housing of the same size the all in black finished and completely new developed high-end high-speed camera SpeedCam Visario g3 offers a ten times increase of the significant specs - frame rate - image memory - sensitivity/dynamic - compared to the SpeedCam Visario g2. The crash test ability is not killed by that. 12 bit color depth per channel and its image quality lifts it above Cine SpeedCam level. The edge of what is ingeniously feasible, however, is reached - ruggedized compact design versus camcorder functionality, see [SloMo HYCAM].
Because the interfaces are the same for Visario g2 and Visario g3 all the equipment can be used for both, even the same cables. Also like with g2 among others internal harddisk and crash-proofed rechargeable battery are available.

In 2010 the Fraunhofer Institut (FhG) IIS Erlangen, Germany, supplied its camera studio with an additional multi channel system, which can be used by third parties.