November 15

The GIS Monitor was published electronically from August 2000 to December 2007.  Some hyperlinks in the archived content may be broken or out-of-date.  If you need additional information about an inactive link, please contact Professional Surveyor Magazine.

Contents

Editor's Introduction

This week, I bring you the second part of the profile of 3Di West, a photogrammetry, mapping, and GIS company. Plus, two short news items and 27 press releases.

Yesterday, I hope you all had a good GIS Day! I visited a display of maps and aerial photographs by the City of Eugene, Oregon, and an event at the University of Oregon, which included a map competition and a few short presentations.

— Matteo Luccio

Profile of a Photogrammetry Company — Part 2

Last week, I featured the first part of my profile of the photogrammetry, mapping, and GIS company 3Di West. Here, now, are some of the highlights of my conversations with four of the company's managers: Lynn Engel (photogrammetry), Amy Perdue (orthophotos), Luke Savage (GIS), and Leanne Mitchell (project delivery).

Photogrammetry

Lynn Engel describes his job as "a juggling act, trying to get everything prepared and out on some kind of a schedule." In preparation for flying a job, 3Di West contracts with a surveyor, who establishes coordinates and puts out premarks—big white targets of some kind—that can be later identified on the photography. In good weather, photography can be flown within a week of when the targets are in place. Some surveyors will place the targets first, so that the flight company can get started, and then, after it has flown the job, they do their groundwork to figure out the targets' exact coordinates. "That speeds up this whole process," Engel says, "because now, while the flight is being taken and then the film is developed and scanned, the surveyor is out doing his groundwork."

Once an aerial photography subcontractor has taken the photos, they are scanned on a special high resolution photogrammetric scanner and sent to 3Di West as a digital file. This is where the in-house process begins. Photogrammetrists identify the targets and tell the software in which photos they appear; they then pick photo-identifiable points in other locations—such as sidewalk corners or the ends of stop bars—and identify those points in every photo in which they appear. "The software then does an adjustment," Engel explains, "and makes all these photos fit together exactly the way in which they were flown. We then import that set of measurements into PATB, a special aerotriangulation (AT) package that does a least-squares adjustment. It does a very good job of pointing out mistakes, blunders, and weak areas." The photogrammetrists can then fix the problems or troubleshoot them with the surveyor.

The photogrammetrists then load the file into Socet Set (a 3D viewer developed by BAE Systems originally for the U.S. military), put on stereo glasses, and begin the aerotriangulation (AT) process to correct the information. This process establishes a centerpoint for each photo; mathematical formulas then allow the software to determine the coordinates for any point on the ground, based upon those targets that the surveyor provided and the position of the camera when the photo was taken.

Photogrammetrists can then begin to create a base map, in as much detail as the client needs—drawing lines for such features as the top of the curb, the bottom of the curb, the centerline of the road, the edges of driveways, the outlines of houses, fences, manhole covers, and power poles. "The same thing can be done by a survey crew on the ground," says Engel, "by simply going out and establishing coordinates for all of these different features. This business started and has grown because we can do a much greater area in much less time than what a survey crew can do on the ground."

The photogrammetrists, also referred to in this context as data collectors or compilers, spend almost 100 percent of their time doing this digitizing of roads, sidewalks, buildings, break lines, pond, rivers, etc., which is the most time-consuming part of the whole process. "Depending upon the density of development," Lynn says, "it can take anywhere from a few hours to several days to collect that information for a model." They then pass the data on to editors, who clean it up and pass it on to other technicians to create maps, orthophotos, and GIS databases.

3Di West has about 50 of these projects going at any given time. Most of its photogrammetrists have a college degree of some sort. However, Engel points out, only one college in the United States has a degree in photogrammetry, so most of them started someplace else: he has a degree in surveying, four of the company's staff have degrees in geography, a couple have degrees in GIS, and a couple started out without any degrees related to this type of work. "Mostly," says Engel, "we train them from scratch."

Orthophotography

The orthophotography department takes the Digital Terrain Models (DTMs) and other planimetric files created by the compilers and—using such elements as break lines, layers, mask points, elevations, and road edges—ties them together geographically with the aerial photography to make photomosaics.

In order to make a photomosaic of a large area or align it to a PLS grid or an entire county, the technicians must choose the best part of each digital scan. Usually, this is the center of each photo, which has the least distortion. At times, however, they will make exceptions to this rule in order to ensure that a feature, such as a large building, is taken entirely from one photo. "We really try to choose the best possible, most nadir (vertical), part of the photo that is going to be used in this mosaic," Amy Perdue explains. "Then we have to tie together the map and the image so that they can overlay and everywhere on this photo is geographically accurate."

Typically, 3Di West works with cities, counties, and private surveyors and engineers, on areas covered by two to four dozen aerial photos and flight lines. However, when I visited, the orthophotography department was working with a large county, consisting of nearly two thousand images. "This is one of the rare ones that we get and everyone ends up working on," says Perdue.

These geographically rectified mosaics then must be color-balanced. "We take them into a couple of different programs to clean out artifacts, such as anything that went on the scanner or the film when scanned," Perdue explains. "It could be a bit of fuzz, hairs, or a little bit of glue on the edge of the film. All of that shows up as white specks that we need to clean out. We take that into Photoshop or Corel. Sometimes, when the film is scanned, and we get it in digital format, the colors may have been toned down or deadened a little bit, so we want to pump up that histogram to make it really look like it is supposed to look. And, because we have seamed together all of these images, we want to make sure that those seams are not visible. We want it to look like a single image, not a patchwork. We use ArcView for displaying the photos." Another concern is minimizing the banding effect due to the flight lines.

Amy has two displays on her desk: a huge CRT and a flat-screen LCD. "Most of our clients are leaning toward the LCD screens now," she explains, "but we know that true color really is on the CRT. So, we want to make sure that we balance between the two types of screens, so that it does not look garishly oversaturated on one and totally dull on another."

Sometimes the resolution on these photos is so high that it is possible to tell the makes of cars. "Some DOT project we worked on," says Perdue, "had a resolution of 1/10 of a foot. You are not just digitizing a street centerline, you are digitizing along the outside edges of the line!"

Except in the case of some engineering firms that need only maps, most of 3Di West's projects come through this department before going out to the clients. In most cases, this is the last stop. "We do a lot of burning here," says Amy, referring to the creation of data CDs. "It goes through all the other steps then it comes to us and it is up to us to go back through the project and check that we have met all of our requirements." An increasing number of projects, however, include one more stop: the GIS department.

GIS

For years, 3Di West translated data into GIS formats, using ArcGIS, and massaged it for GIS deliveries. A couple of years ago, the company started a GIS department. Besides in-house dataset translation work, it does external consulting work for a variety of GIS projects. In addition to Luke Savage, it has a GIS technician in Eugene and a GIS analyst in Boise, Idaho.

"We primarily deliver needs assessment and strategic planning services for GIS implementation," says Savage. "We can help a city through the process of setting up a GIS, as a team member. Everybody else out there is offering software-based solutions and pushing their bias as to how they think that GIS should be for a given organization. We are approaching it on a more consulting side. We are helping them understand their workflow and the idiosyncrasies within their organization and then providing recommendations and options regarding different software packages that are out there, different implementation strategies and costs. We lay different options on the table and help them choose a strategy. Then, we can help them implement it or they can have somebody else implement it."

While 3Di West has a development partnership with Autodesk and is an ESRI business partner ("I don't know of anybody else out there who does GIS that isn't!" says Savage), it is not an ESRI reseller, nor does it develop and sell its own software. Therefore, Savage says, its consulting is not biased toward a particular software.

Whenever a contract includes a GIS delivery, the editors pass the data to the GIS department, which gets it ready to port it into GIS. If it needs to build triangulated irregular networks (TINs), it gets somewhat different datasets then the orthophoto department, because it adds in the road edge and many features that are not required in orthophotos. To QC the data, the GIS staff overlays it on top of the orthophotos. "If we have an overlap feature," Savage explains, "we use our GIS to build topology, which is just another way to bring intelligence to the data and putting in rules to say 'this feature can't overlap this feature.' So, if we see an overlap, we can automatically zoom down to it, highlight it, see what kind of error it is, and manipulate it. If the error is greater than our tolerance standard allows, we send it back to the editors and ask them to fix it. In ArcGIS we can zoom right into errors at .001 feet or .001 meter and fix them for the GIS delivery." When required, the GIS staff will spatially join additional datasets and merge the attributes into the datasets for delivery.

Savage has experience with open source and likes Autodesk's approach to open source with MapGuide. It allows him to give clients the choice between the enterprise edition, which is supported, and the open source solution, which is free; both require customization.

"I rarely say GIS anymore. I call it spatial intelligence, because it's morphing into something different," says Savage, who has a degree in geography and a background in urban planning. "Geographers have a theory and use the tools to come up with the results. We are not tied to one vendor. And that is how we, here at 3Di West, are approaching our services to others. We are not vendor specific."

As an example of a consulting project, Savage cites a client in Pocatello, Idaho, for which the company does mapping services. "They were having some problems with their ArcSDE database," Savage says. "We told them that we could help them in that area. I assessed the database, how it was designed, and what they want to do with it and it was not quite right. So I redesigned it and implemented a better ArcSDE database solution for them and tuned it for performance." The client then asked Savage to help them port the application to the Web. So, working directly with the client's IT staff, he set up security parameters to serve data out to the public, fine tuned their servers, designed the architecture, and recommended ways to improve the system's performance and usability.

"I use servers here to test out the integration," says Savage. "That way, when I go onsite, I know how it is going to work and if I see any issues I've probably seen them before. So the implementation is a lot quicker and smoother and if there are any problems I can fix them very quickly. Many software vendors try to implement in production something that they haven't fully tested."

"Part of the problem with GIS," Savage argues, "has been on the implementation side, because these two worlds—IT and spatial—are not talking to each other. Now clients increasingly require people who have both of those knowledge bases. That's where I come in."

Another example that Savage showed me was a website for Bonneville County, Idaho, for which 3Di West designed a parcel map viewer with a config file that allows the county's IT staff to add reports. For this project, 3Di West partnered with ProWorks, a Microsoft application development firm that does a lot of AI design for NASA and the FAA. "I wanted somebody who knows IT, because I know the GIS side," says Savage. "I wanted someone who knows the intricacies and the latest technologies and the best way to implement those latest technologies. We don't try to specialize in everything. Our GIS department is maturing its capabilities, but we really want to provide good, smart solutions and services for our clients."

Project Delivery

"A happy client is a good client," says Leanne Mitchell. "We're trying to make sure that we have fewer loose ends when a project is finished. We've always tried to do that, but a lot of work has come through this office in the last few years, so we've had to change our management design a little bit." Sometimes she is on projects from the very beginning, so as to understand the requirements. "My duties involve more than just final delivery. I do proposals, make estimates on projects, talk to clients."

The first thing that she does at the start of a job is to make sure that the surveyor knows where the controls need to be. Then, as soon as the premarks are down, she gives the flying company the go ahead and coordinates tasks so that they take place quickly and efficiently.

Once the job gets in-house and starts going through the AT process, Mitchell makes sure that the product goes through some sort of QC process at every step of the way. "When it goes into AT," she says, "if there is any problem with the survey—usually, it is really tight—we tidy things up there, make sure that everything fits well, before it goes into the stereo compilation phase. In the end, I'd say that 80 to 90 percent of the work gets thoroughly QC'd by a senior compiler. If there are specific features in a job that we don't understand, I meet with Lynn and we figure out what the client is looking for. Do we need to consider any special collection strategies to pass on to the stereo compilers?"

The final deliverable used to be a CAD product. Now, increasingly, the company's larger clients are requiring a GIS deliverable. "I am bridging the communication gap between the two," says Mitchell. "I am trying to encourage our staff to do more QC of the final product. Because what comes out of our CAD department, as much as we try, isn't going to be perfect or what we'd like to give to our clients."

"In the past," says Mitchell, "we were so CAD-based and so hard copy map-based that we used to break large cities up into 2x2 sheets of data that were all indexed and referenced to each other. We would deliver 25 or 50 of those for a project. It is a lot of work for us and it is a lot of unnecessary CAD file data that our clients don't need any more, so I'm trying to pull us out of that old routine."

"After stereo compilation has finished its work and the QC person goes through and cleans it up, the file goes to the CAD editor, who generates the file contours and beautifies it a little bit, trims all the dangles, and nodes things together." All CAD work is done by a full-time CAD editor, a part-time editor in the company's Boise office, and a former employee who now operates as a subcontractor.

"In the past, a majority of our clients were engineers who wanted CAD data and not GIS data, so we were used to delivering most of our features as point and line data with annotations. Almost all of our deliveries include both CAD data and imagery. We also have more and more cities, counties, and other large clients wanting, at a minimum an importation of the CAD data into a geodatabase."

Increasingly, the company's clients require more refined, completely polygonized CAD data that they can use in their GIS. This is something that the company's photogrammetric software isn't intelligent enough to do. "Take a driveway, for example," says Mitchell. "You want to create a polygon out of a driveway, that sounds pretty simple, but you have building lean issues, and, depending on what side of the building you are on, it can affect the horizontal accuracy and sometimes the vertical accuracy of that data. So we found it easier to collect the data in a stereo setting that makes most sense in terms of accuracy and then just handing it over to the edit and GIS departments to come up with a way to batch-process the feature extraction in 2D that is in the end needed in a geodatabase."

While more and more cities are more comfortable using GIS, Mitchell explains, some cities for which 3Di West has done work this year still required a CAD delivery because they do a lot of contracting work with engineers.

Some of the thorniest issues in project management, according to Mitchell, are technical details. For example, after 3Di West upgraded to ArcGIS 9.2 it found out that it has a client that uses only 9.1 and you can't have them both on the same system. "I've been the conduit of communications between CAD delivery and GIS delivery, trying to smooth over some things and having some better understanding between the two. GIS users haven't dealt with a lot of CAD data and CAD users haven't dealt with a lot of GIS data and they don't really know what each wants or needs. I am kind of in the middle and I end up looking at a lot of data, in CAD or in ArcMAP, trying to figure it out from both sides."

Another issue that sometimes bogs her down is clients not knowing quite what they want. "I try to ask the right questions to draw that out of them."

Briefly Noted

According to today's New York Times, the Los Angeles Police Department has shelved a plan to map out Muslim communities, a proposal that civil rights groups had sharply criticized as racial and religious profiling. Under the plan, the LAPD's counterterrorism bureau would have identified Muslim enclaves to determine which might be likely to become isolated and susceptible to ''violent, ideologically-based extremism.'' Using data that would have been assembled by the University of Southern California's Center for Risk and Economic Analysis, the project would have examined the history, demographics, language, culture, ethnic breakdown, socioeconomic status, and social interactions of the estimated 500,000 Muslims in Los Angeles, Orange, and Riverside counties.

According to National Public Radio, Google will install its maps feature at some gas stations next month. About 3,500 gas pumps will be fitted with an Internet connection and a small color screen. You can type in where you want to go and the pump will display a map and print directions.

» Back to our GIS Monitor NOV 2007 Issue