GIS Technology Trends in Scanning and Plotting: What's New and What's Next

By Michelle Sheldon , Océ North America, Inc.
August 21, 2007

The history of GIS dates back roughly 50 years to a time when thematic maps were drawn or plotted on translucent film, then physically laid on top of each other to create a composite image. In the last five decades, GIS technology has evolved from a labor-intensive physical pursuit to one that operates with powerful software-based systems.

A data collection revolution
GIS data capture can come from remote sensing and surveying, or it can be derived from non-digital sources through digitization and scanning. Data collection and conversion has traditionally been the most expensive and time-consuming aspect of GIS projects.

The tablet digitizing process historically existed as an acceptable method for creating data points with x and y values. However, this time-draining process was often fraught with challenges - difficulty using the digitizing puck, tablet malfunctions, source materials changing size, registration problems, edge-matching complexity and more. Those days are drawing to a close.

With today's more advanced digitizing methods, it is now possible to scan in a map, bring the scanned map into a GIS, georeference the scanned map, zoom in on the screen and digitize select features. This revolution in technology means users can zoom in on images as much as is needed, digitize using a computer mouse, and more easily edge-match for faster map creation.

Océ TCS500 scanner in use.

Scanner choices and considerations
The convergence of GIS and scanning presents users with a myriad of choices, the most important being which type of scanning technology to use - reduction type or contact image sensor.

Reduction type scanning is similar to the technology used in a traditional camera. An image is reduced through a single camera lens and focused on a sensor, which captures the image based on intensity of light passing through the lens. This creates images of much higher quality than contact image technology; however, since scanners are typically separate from the printing system, it requires a larger footprint. This is most often used for applications where quality is at a premium.

In contact image sensor scanning, an array of fiber optic lenses is directly connected to image sensors that capture information. Because this is a more compact technology that can be used in conjunction with a printing system, it consumes a smaller footprint. However, the images produced are of a lower quality than those made using reduction type scanning. This is most often used for lower-end, consumer-type applications.

In deciding on a scanning technology, keep in mind the following considerations:

• How important is depth of field? Reduction type allows for a larger depth of field, which can be critical when scanning folded or very old documents
• For your needs, will a single camera lens suffice? Contact image (multiple lens) technology lends itself to smaller, more portable scanners, but requires frequent calibration. Reduction type (single lens) produces higher quality and consistent color with no need for image "stitching"
• How important is warm-up time? Innovative new lamp technology is now available on many scanners, which eliminates warm-up delays (typically 10- to 60-minute delays with traditional fluorescent lights) using instant-on capability
• How important is light quality? No matter what scanner you choose, it's important that the illumination is projecting correctly in order to ensure consistent, accurate color and highest quality output

Workflow enhancements from smarter scanners
Unlike the limitations of scanners past, the advanced features of state-of-the-art scanners actually help to improve GIS workflow:

• Enhanced ease-of-use - the elimination of warm-up wait time and the availability of customizable job templates for scan-to-file and copy operations enable users to get proper job settings with a one-button operation
• Concurrent processing - today's technology supports concurrent job processing - greatly accelerating workflow by allowing simultaneous scanning, processing, ink refills and paper changes
• Automatic image clean-up technology - software is now available to automatically enhance scanned images by analyzing originals on a pixel-by-pixel basis, ensuring only appropriate information is captured

Improvements both in the understanding of what constitutes successful GIS scanning and the technology that supports advanced scanning have set the stage for a leap forward in making GIS-based "smart maps." The availability of high-quality reduction type scanners with easy-to-use features (instant-on, one-button operation, clean-up features, etc.) means there is significant potential for advances in GIS-based cartography.

The power of advanced plotting
Scanner improvements are not the only systems aiding the advancement of GIS technology. New generation plotters are also making an essential contribution.

Over the years, legacy inkjet plotters have been showing signs of strain. Such aging technology can adversely impact workflow and lead to a number of challenges including:

• Insufficient processing power as file sizes grow
• Unsuccessful plot attempts due to limited file processing visibility
• The unnecessary addition of plotters to cope with plotter bottlenecks
• No built-in intelligence to optimize print speed and quality
• Absence of back-channel communication
• The inability to remotely monitor and view plotters
• The need to re-send files after quick check plots
• A lack of upgradeability to meet changing requirements

The technical advances of today's inkjet plotters, however, make such challenges passé. Newer plotting solutions support continued growth in GIS and the evolution of paper maps, enabling:

• More robust file processing - new generation of inkjet plotting technology from Océ, for example, offers significantly greater printing power, virtually eliminating wait times and increasing both hard disk capacity (up to 80 GB) and memory (as much as 1 GB)
• Concurrent processing - plotter controller architecture now affords the power to process, plot, copy and scan simultaneously
• Optimized print quality/speed - users no longer have to sacrifice speed for quality - today's technology automatically optimizes for both
• Versatile ink/media management - the latest inkjet printers enable users to change ink tanks and media while printing is in process, making it simple to match the right media size with varying print jobs for the desired output size
• Color emulation - pre-calibrated color management modes make it possible to replicate the color of jobs produced on legacy inkjet devices, emulating colors to adhere to specific shade requirements and branding guidelines
• Print queue management - advanced management capabilities make it easier to control workflow and meet demanding deadlines by allowing users to prioritize rush jobs, place certain jobs on hold and even change the settings on already-processed jobs
• Upgradeability - modern inkjet plotters, with their ability to be functionally upgraded rather than replaced, actually help to extend the value of your investment

The future of GIS is bright
The overall growth in GIS applications is creating the need for more complex and sophisticated scans and plots. Today's technology is answering the call. Advanced tools for scanning and plotting not only tackle increased plotting demands, they are converging to create new, innovative ways to enhance the speed and quality of cartography - all while improving workflow and reducing costs.

Technology developments like robust controller architecture for larger processing capacity, concurrent processing, improved ink and media management, and visibility and control of print jobs are currently available to address the challenges of the past and help pave the way to a brighter future for GIS users.

Visioneer - OneTouch 9020 USB review

This is the only one of the six scanners to be designed as a landscape device; wider than it is deep. Depending on how and where you're going to use it, this layout could be convenient. There are five easy-use buttons along the scanner's long edge, which initiate scan, copy, OCR and e-mail functions. The fifth button is programmable to launch an application of your choice.

One of the highlights of this scanner is its Scansoft PaperPort software. This provides good control of your scanned documents and enables you to feed them directly into the appropriate application, so OCR documents go to your word processor, while colour prints are scanned to a graphics program, such as the excellent Photoshop Elements which is bundled with the scanner.

The OneTouch 9020 comes with a transparency adapter built into its lid. While it only scans a single slide or negative at a time, it does so quickly, completing the scan in under 30 seconds. Other scans are also commendably quick for a device of this price, with the 8 by 8-inch colour print scanning in just 12 seconds.

Scan results were not that good, with an unpleasant yellow cast over skin tones by default. You can compensate for this, using the well-designed scanning interface in the Visioneer driver, but it's annoying that you can't get better results without adjustment. Compensating for scanning shortcomings is made easier by the facility to save and reload custom presets from within the driver. Overall, the specification and facilities of the OneTouch 9020 are good, but scan quality is below par in its default mode.

Umax - Astra 4700 + TPU4500 review

Umax offers a two-part solution for scanning; its scanner and the optional transparency adapter. The scanner can be bought on its own for around £100. The adapter sits like an ice-hockey puck on the glass of the flat-bed and can handle a variety of media, from 35mm slides to negatives in several sizes. Many of the transparency adapters included with entry-level scanners are pretty cursory and this device is better made than most.

The design of the Astra 4700 is fairly conventional, but with only three special-function buttons at the front. These enable one-touch scanning, copying and e-mail, but other tasks have to be initiated from within the scanning software.

The Umax driver looks slightly simplistic at first sight, but a strip of extra buttons, initially hidden, broadens its scope. It can, in fact, handle most of the tasks you might set it. The scanner comes bundled with MGI's PhotoSuite and the PaperCom document manager. Both of these applications are useful in their own right and work well with the scanner.

Scanning speed for the Astra 4700 was quite impressive, with the 8 by 8-inch print completing in a group-leading seven seconds, but scanning the 35mm slides took over a minute, which was not so quick. The A4 text scan, important for OCR work, took just 13 seconds.

Image quality was reasonable, with fair reproduction of colours, though darker hues could look a little lifeless. Reproduction of line art was a little better than we had expected, and better than the subjective results our sample images suggested. Overall, this scanner and transparency adapter is a flexible combination at a competitive price.

HP - Scanjet 4570c review

Several unexpected features single this scanner out from the crowd - though not all of them are good. For a start the device is much longer than most A4 scanners, with an extended lip at the front, into which is set a two-digit LCD display and no fewer than eight buttons. While the number display may be useful if you use the scanner for a lot of copying, and it may well be handy to switch between colour and greyscale scans from the button panel, none of these extras is vital.

All the software supplied with the Scanjet is integrated into one HP application and this installs well, though it's not always easy to use. The scanner driver, in particular, has the annoying habit of resetting any parameters you set, at the end of a session. This makes it particularly awkward when you're using it from a third-party application, such as Photoshop or Paint Shop Pro.

The transparency scanner takes the form of a separate unit which you lay on the flatbed in the middle of a template which exactly fits the scan bed. It can scan three slides or a strip of negatives in one go, but is still not as easy to use as the built-in adapters fitted to other scanners.

The performance of the Scanjet 4570c was on a par with the Epson scanner on the print and text page tasks, but it completed the transparency scan in less than half the time, the fastest in thegroup. Image quality was good even at the default settings and it's only the irritating shortcomings in some of its software that holds it back.

Epson - Perfection 1660 Photo review

This is a big, beefy scanner and although it costs more than some of its competitors in this group, it also produces above average results. It sits quite high off the desk and makes a fair amount of noise when scanning, with as many buzzes and clunks as the Canon device.

A row of buttons along its front edge, including a convenient, illuminated scan button, offer one-touch copy, e-mail and scan-to-Web functions. A transparency adapter is built into the scanner's lid and it can cope with up to four slides at once, or a complete strip of 35mm negatives.

There are just two sockets at the rear of the Perfection 1660 Photo, for USB 2 and power connections. Epson's own scanner driver is easy to use and well-functioned, but if you need more photo processing muscle you can call on either ArcSoft's PhotoImpression 4 or Adobe's Photoshop Elements, both of which are bundled. Photoshop Elements, while a cut-down version of Adobe's flagship painting package, still has most of the more useful tools and filters in that product's feature-set.

Scan times for the 8 x 8-inch colour print and text page tests were impressive at 9 and 10 seconds respectively, though the transparency scan, of a single slide, was a little slow at 65 seconds. For day-to-day scanning, this is the fastest device in the group.

It also produced some of the best quality scans, straight from the box. Images were lively, without being over-vivid, and pastel colours reproduced accurately and close to their originals. The Perfection 1660 Photo is a good general-purpose scanner at a very reasonable price.

Canon - CanoScan 3000F review

The cheapest of the six scanners in this group, the CanoScan 3000F is surprisingly well-equipped. Although little bigger than an A4 sheet, it uses a proper cold cathode lamp for illumination, as do all the scanners in this group, rather than the LED strip employed by some entry-level devices.

It uses what Canon calls a Z-hinge to enable the convenient scanning of thick books and it has a transparency adapter built in. This is revealed by sliding off a white plastic cover from the underside of the lid and you can then scan a slide or a single frame of 35mm negative. Three buttons on the scanner's front edge provide one-touch scan, copy and e-mail functions.

Installation is straightforward; install the software, connect the USB 2 cable and plug-in the power supply. Canon's flexible ScanGear driver has both beginner and expert modes and ArcSoft's PhotoStudio editing software and PhotoBase for image management are also supplied. PhotoStudio, although not one of the best-known editing packages, includes a good range of tools and filters.

The CanoScan 3000F is not the fastest scanner in this group, taking 18 seconds to scan an 8 by 8-inch colour print and nearly a minute for a 35mm transparency. It's also not the quietest, making a variety of whizzes and clunks during the scanning process.

Scan quality is in general acceptable, though flesh tones can come out with an over -pink tinge. This is easily adjusted for, though it would be more useful to have the defaults correct from the start. Overall, this is a neat, high-spec scanner for its asking price.

Color Scanner Characterization

Mathematically, the recording process of a scanner
can be expressed as
ci = H(MT ri)
where the matrix M contains the spectral sensitiv-
ity (including the scanner illuminant) of the three
(or more) bands of the scanner, ri is the spectral re-

ectance at spatial point i, H models any nonlineari-
ties in the scanner (invertible in the range of interest),
and ci is the vector of recorded values.
The characterization problem is to determine the
continuous mapping Fscan which will transform the
recorded values to a CIE color space. In other words,
determine the function Fscan such that
t = ATLr = Fscan(c)
for all r 2
r , where
r is the set of physically re-
alizable re
ectance spectra, the columns of matrix A
contain the CIE XYZ color matching functions, and
the diagonal matrix L represents the viewing illumi-
nation.
For the non-colorimetric scanner, there will exist
spectral re
ectances which look dierent to the stan-
dard human observer but when scanned produce the
same recorded values. These colors are dened as be-
ing metameric to the scanner. Likewise, there will
exist spectral re
ectances which give dierent scan
values and look the same to the standard human ob-
server. While the latter can be corrected by the trans-
formation Fscan, the former cannot.
On the upside, there will always (except for de-
generate cases) exist a set of re
ectance spectra over
which a transformation from scan values to CIE XYZ
values will exist.
Printed images, photographs, etc. are all produced
with a limited set of colorants. Re
ectance spectra
from such processes have been well modeled with very
few (3-5) principal component vectors [1, 2, 3, 4].

When limited to such data sets it may be possible
to determine a transformation Fscan such that
t = ATLr = Fscan(c)
for all r 2 Bscan where Bscan is the subset of re-

ectance spectra to be scanned.
Look-up-tables, nonlinear and linear models for
Fscan have been used to calibrate color scanners
[5, 6, 7, 8]. In all of these approaches, the rst step
is to select a collection of color patches which span
the colors of interest. Since the particular samples se-
lected determine the characteristics of the mapping,
the scanner characterization is usually identied with
respect to the process which produced the samples.
Ideally these colors should not be metameric in terms
of the scanner sensitivities or to the standard observer
under the illuminant for which the characterization is
being produced. This constraint assures a one-to-one
mapping between the scan values and the device inde-
pendent values across these samples. In practice, this
constraint is easily obtained. The re
ectance spectra
of these Mq color patches will be denoted by fqgk for
1  k  Mq .
These patches are measured using a spectropho-
tometer or a colorimeter which will provide the device
independent values
ftk = ATqkg for 1  k  Mq:
Without loss of generality, ftkg could replaced with
any colorimetric or device independent values, e.g.
CIELAB, CIELUV. The patches are also measured
with the scanner to be calibrated providing fck =
H(MT qk)g for 1  k  Mq .
Mathematically, the characterization problem is:
nd a transformation Fscan where
Fscan = arg(min
F
Mq
X
i=1
jjF(ci)􀀀L(ti)jj2)
where L(
) is the transformation from CIEXYZ to the
appropriate color space and jj:jj2 is the error metric in
the color space.

Scanner...

scanner is a device that optically scans images, printed text,handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop (or flatbed) scanner where the document is placed on a glass window for scanning. Hand-held scanners, where the device is moved by hand, have evolved from text scanning "wands" to 3D scanners used for industrial design, reverse engineering, test and measurement, orthotics, gaming and other applications. Mechanically driven scanners that move the document are typically used for large-format documents, where a flatbed design would be impractical.

Modern scanners typically use a charge-coupled device (CCD) or a Contact Image Sensor (CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. A rotary scanner, used for high-speed document scanning, is another type of drum scanner, using a CCD array instead of a photomultiplier. Other types of scanners are planetary scanners, which take photographs of books and documents, and 3D scanners, for producing three-dimensional models of objects.

Another category of scanner is digital camera scanners, which are based on the concept of reprographic cameras. Due to increasing resolution and new features such as anti-shake, digital cameras have become an attractive alternative to regular scanners. While still having disadvantages compared to traditional scanners (such as distortion, reflections, shadows, low contrast), digital cameras offer advantages such as speed, portability, gentle digitizing of thick documents without damaging the book spine. New scanning technologies are combining 3D scanners with digital cameras to create full-color, photo-realistic 3D models of objects.

Types

• 1 Drum
• 2 Flatbed
• 3 Film
• 4 Hand

Quality

Scanners typically read red-green-blue color (RGB) data from the array. This data is then processed with some proprietary algorithm to correct for different exposure conditions, and sent to the computer via the device's input/output interface (usually SCSI or bidirectional parallel port in machines pre-dating the USB standard). Color depth varies depending on the scanning array characteristics, but is usually at least 24 bits. High quality models have 48 bits or more color depth. The other qualifying parameter for a scanner is its resolution, measured in pixels per inch (ppi), sometimes more accurately referred to as Samples per inch> (spi). Instead of using the scanner's true optical resolution, the only meaningful parameter, manufacturers like to refer to the interpolated resolution, which is much higher thanks to software interpolation. As of 2004^[update], a good flatbed scanner has an optical resolution of 1600–3200 ppi, high-end flatbed scanners can scan up to 5400 ppi, and a good drum scanner has an optical resolution of 8000–14,000 ppi.