How to use Negative Distances in your Geospatial Buffer Analysis

Geospatial buffer analysis involves generating a polygon at a specified distance from a proposed feature to determine proximity. For example, a 100m buffer around a point feature creates a circle with a 100m radius. Similarly, a 50m buffer around a polygon feature creates a larger polygon – a polygon that encompasses the source feature.

However, did you know that you can also use a negative distance to create a buffer? That’s right! When you use a negative distance, such as -25m, to buffer a polygon feature, the result is a smaller polygon – a polygon that is inside the source feature.

Consider the following example where the objective is to determine the area of shoreline habitat available for a certain species of wildlife. The species in question has been observed not to forage beyond 100m from shore and includes a riparian buffer of 25m as part of its habitat. To compute the total area of habitat available to this species requires the creation of two buffers and a polygon overlay operation. The first buffer (ie BufferOutside25) is created at a distance of +25m and represents the riparian buffer. The second buffer (ie BufferInside100) is created at a distance of -100m and represents the forage extent. A polygon overlay analysis of type subtract is then used to determine the zone of available habitat where:

HabitatZone = BufferOutside25 – BufferInside100

The total area of habitat available is equal to the area of the zone of available habitat (ie HabitatZone).

Check out the video to see the process in action with AutoCAD Map 3D.

Engineering GIS in LEED for Neighborhood Development

Leadership in Energy and Environmental Design (LEED) is a certification program that encourages the adoption of sustainable design, construction and operation practices as applied to buildings and communities. Think of LEED as a way of promoting a green approach to community development.

From a civil engineering perspective, LEED for Neighborhood Development (LEED ND) is an opportunity to bring together engineering design and GIS analysis methods in order to meet a set of documented requirements for achieving LEED certification. For example, the Smart Location and Linkage category encourages brownfield developments to reduce urban sprawl. Maximum credit can be attained if the project is located in a previously developed infill site that is also in a high-density area. In this case, high-density is a function of the number of street intersections within a half-mile of the project boundary.

To determine how well a project complies with these criteria, we can apply an Engineering GIS approach that leverages both CAD and GIS data. First, rather than using an import/export method to bring together the required data, FDO data providers are used to connect the GIS-based parcel and street centerline data to the CAD-based site design. Next, a geospatial buffer is created at a distance of a half-mile from the site boundary. The buffer is used to determine proximity and involves generating a polygon at a specified distance from the proposed site boundary. Finally, in this simplified example, a geographic query is used to determine the number of intersections within the buffer and this number is compared to the LEED criteria.

Some of the benefits of this approach include the following:

• Data conversion and data redundancy can be avoided as a result of using FDO data providers to connect to the data directly rather than relying on an import/export process.


• Efficiency is improved as a result of applying an approach that embraces CAD tools for site design and geospatial tools for analysis all in one software platform.


• Better designs are possible because more design alternatives can be evaluated against LEED criteria.
  

Check out the video to see the process in action using AutoCAD Map 3D.

Cowboys, Barbeque and Geospatial Analysis

Yee Haw! It’s Stampede Week in Calgary, Alberta and what better way to celebrate than to combine Stampede attire (ie cowboy hat, jeans, big belt buckle and boots) with a seminar on Geospatial Analysis. Well, it seemed like a crazy idea; however, the folks at Autodraft, Inc have a great sense of fun. So, when I was given the opportunity to talk about my favorite topic of Engineering GIS and CAD/GIS integration, I jumped at the chance.

In spite of the Stampede traffic, the rain and the tornado watches, folks came out in droves to learn how to analyze their CAD drawings and geospatial data using the powerful geospatial analysis tools found in Engineering GIS. With the help of my pardner "Cowboy Bob", we delivered a seminar entitled "Geospatial Analysis for the Egnineering and CAD Professional". We used AutoCAD Map 3D, AutoCAD Raster Design and Autodesk Topobase to demonstrate numerous geospatial techniques including…

• Queries and how to use them to get more information from CAD drawings and GIS data sources
• Drawing cleanup tools and why they are necessary to ensure the accuracy and correctness of CAD and GIS data
• Topology, it’s importance for CAD and GIS users alike and how to create topologically correct features
• Spatial analysis such as network traces and their use with CAD and GIS data
• Polygon overlay and its power to reveal new patterns in CAD and GIS data
• Buffer analysis and why it’s sometime the best way to determine spatial proximity
• 3D surfaces and how to analyze them for height, slope and aspect
• Raster to vector conversion and how to combine scanned CAD drawings, maps and aerial imagery with vector-based CAD and GIS data
• And more…

After the presentation, we all moseyed on down to the Autodraft corral for a great Stampede barbeque, refreshments and conversation.

A fun and informative Yee Haw time was had by all!

New Online Resource: GIS Skills for Engineers

Over the last several months, I have had the pleasure of facilitating a number of seminars in Canada and the United States aimed at demonstrating the six crucial GIS skills needed by Engineering and CAD professionals. I have blogged about this seminar series in the past. This time I want to call your attention to a great resource entitled GIS Skills for Engineers that is now available via the web. This resource is part of Autodesk's help documentation for AutoCAD Map 3D and highlights a number of important GIS skills including:

Data Preparation
Data Conversion
Data Access
Data Editing
Data Management
Styling and Theming Features
Analysis
Sharing Data with Others
Map Layout and Cartography
Printing, Plotting, and Publishing

The best part of GIS Skills for Engineers is the accompanying animations which demonstrate the skills in action. For example, if you wanted to know how to perform a polygon overlay analysis to determine which parcels in a city fall within zones classified as “Retail”, check out this animation.

Free Engineering GIS Software for Unemployed

Autodesk, Inc recently announced a new program called the Autodesk Assistance Program. According to Steve Blum, Senior Vice President America's Sales for Autodesk, the program is designed to help the unemployed advance their career during this challenging job market.

Among other things, the program offers:

• Free software
• Free online training

One of the software packages offered by Autodesk through this program is AutoCAD Civil 3D.

Recall that in some of my previous posts, I discussed the need for Engineering GIS. Well, built on top of AutoCAD Map 3D and AutoCAD, AutoCAD Civil 3D is a true engineering GIS platform and complies with all five Engineering GIS requirements, namely:

• Data throughout the lifecycle
• Native data access
• Engineering design tools
• Geospatial tools
• Accurate renderings

If you are currently unemployed and interested in investing some of your time to retain existing skills or get the new Engineering GIS skills you need, check out the details of this program here or be sure to tell a friend in need.

The Obstacles to CAD/GIS Integration

In my last post, I discussed a need to address the issue of CAD/GIS integration during the design and data creation phases of a project rather than waiting until the data was ready to be moved into a corporate database. The responsibility to address this issue would rest with the creators of the data (ie the engineering and CAD professionals). The reason, I argued, was one of efficiency; that is, data that was properly structured during the front end of the data lifecycle would be easier to integrate throughout all downstream infrastructure related activities, thereby, saving time and collectively, billions of dollars.

So, why does the problem of CAD/GIS data integration continue to persist and negatively impact organizations? Why do so many continue to struggle with import/export workflows, work-arounds and the old way of doing things? Why does CAD/GIS integration remain an issue today?

Well, a number of reasons come to mind…

Data Issues: First there’s the data. Sometimes CAD/GIS data integration problems really are due to the differences in the data – differences such as the use of project coordinates versus geographic coordinates; the need for annotation (ie dimensions, callouts and other explanatory text) versus topology; the use of complex geometries (ie spline curves and 3D objects) versus the limitation of geospatial databases to store them. To a lesser extent, data formats can also be an obstacle as one attempts to massage the data from one format to another potentially introducing errors and redundancy in the process.

Organizational Structure: The way an organization is divided into its various departments and workgroups impacts communication and the flow of data throughout the organization. With respect to GIS, organizations have typically assigned GIS responsibilities and functions to the GIS Department or to a subgroup of the IT Department. This organization based separation of CAD and GIS, can create a communication gap between the data creators (ie the engineering and CAD professionals) and the maintainers of the geospatial data. Then the only time one group communicates with the other is when as-built information needs to be passed to the GIS folks for inclusion in the corporate database. Consequently, the GIS folks don’t understand the problems that can arise when attempting to use geospatial data in CAD and the CAD folks don’t understand the issues related to using CAD data in a GIS. In an attempt to overcome this communication gap between departments, organizations have held Corporate Demo Days, GIS Days and other events aimed at sharing and promoting departmental information, ideas and accomplishments.

Silo Syndrome: Organizational silos occur when departments seem to focus on their own needs without recognizing their impact on other departments or to the organization as a whole. For example, when communication between departments is poor, when the exchange of information is inefficient, or when job related requests are queued and delayed, individuals find ways to work around the problem. They begin to create copies of the data; they create their own databases; and they stop sharing information to help drive their own efficiency. Unfortunately, this can perpetuate the CAD/GIS integration gap and result in greater corporate inefficiencies. To help reduce departmental silos and ensure that both corporate and departmental needs are met, some organizations have embedded GIS responsibilities at both corporate and departmental levels.

Culture Clash: The very things that make us experts in our field also lead to differences in professional cultures. Whether it’s the contrast in educational and professional backgrounds, the knowledge and experience that we gain and share as a group, the jargon, or the type of projects we work on, they all lead to differences in the way we communicate and approach a task. These differences are often additional obstacles to CAD and GIS integration. For example, while a CAD professional is focused on documenting a design in such a way that it can be built to exact design specifications, a GIS professional may be more interested in how this information can be used for planning and analysis after construction. Culture clash seems to become most evident when people balk at the technologies used by others. What’s needed is a respect for both ends of the spectrum. It’s not about CAD or GIS; it’s really about embracing both.

Myths: Myths surrounding the capabilities of CAD continue to persist in spite of significant advances in this technology. Today’s CAD includes model-based design and rule-based workflows; integrates engineering designs with other CAD and GIS data; provides support for geographic coordinates, topologically structured features, spatial analysis and geospatial databases; and simplifies integration with web-based mapping. Rather than continuing to do things the old way because of an outdated view of CAD, current capabilities and new workflows should be examined for gains in efficiency and improvements in data integration.

Lack of Metrics: In the software industry, metrics are used to measure a wide variety of characteristics pertaining to a program’s performance. However, when it comes to the subject of CAD/GIS integration, few organizations monitor the amount of resources required, in terms of time or dollars, to move as-built information into a corporate database. The lack of metrics hides the inefficiencies and the corresponding costs associated with the CAD/GIS integration issue. So, integration challenges go unnoticed and opportunities for improved efficiency escape. Metrics are needed to highlight the CAD/GIS integration problem and to make a case for change.

Discipline Specific Tools: Discipline specific tools were created for a reason. For example, there’s nothing more powerful than the data creation and editing tools available in CAD for creating and documenting an engineering design. Similarly, GIS tools excel at spatial analysis. These discipline specific tools can perpetuate the CAD/GIS integration problem by isolating users from other ways of doing things. Users become accustomed to creating data without topology, storing their data in proprietary formats or using out-dated import/export workflows to facilitate data exchange. While some have attempted to re-create CAD-like functions as custom extensions to their GIS, others have embraced an Engineering GIS approach where CAD and GIS come together exploiting the advantages of both.

What’s In It for Me? Sometimes it just boils down to incentive. Perhaps Rod said it best: “Engineers as consultants or as in house departments are incented in such a way that they do not really care about the life cycle of the data... They just want to hammer out a design and their work stops.” In other words, significant advances in CAD/GIS integration might be made if the creators of the data are contractually obligated to create the data with a new end in mind. CAD standards have been in effect since the dawn of CAD. Perhaps it’s time for a new CAD standard - one that also addresses the downstream data requirements.


The above list represents those obstacles which I have encountered most often in my conversations with a variety of engineering, surveying, CAD and GIS professionals. I’m sure other obstacles exist. If you know of additional obstacles, if you have ideas for solving or eliminating them, if you have related experiences or comments, I would enjoy hearing from you…

GIS Skills for the Engineering and CAD Professional

Last week I had the pleasure of visiting Calgary, Alberta and facilitating a half-day seminar aimed at demonstrating the crucial GIS skills needed by engineering and CAD professionals. This well attended seminar, hosted by Pacific Alliance Technologies, highlighted the differences between CAD and GIS workflows, reviewed the obstacles to CAD/GIS integration and discussed the importance of an Engineering GIS approach.

I was expecting the audience to consist mainly of engineering and CAD folks. So, I was surprised to discover that there was a 50:50 mix of both CAD and GIS professionals. It turned out that some of the geospatial participants were looking for a better understanding of CAD related workflows. They also wanted information on how to work and better communicate with their engineering and CAD counterparts so that they could potentially simplify their geospatial data integration tasks and drive productivity. Similarly, some of the engineering and CAD participants were seeking pointers on how to overcome resistance to GIS within their own engineering organizations.

So, why is there this resistance to GIS by some engineering firms?

Well, engineering is about design; it’s about creating documents that have the exact amount of detail necessary to construct what was designed and then ensuring that construction proceeds according to specification. To these firms, construction represents completion and so their design documents and as-built drawings reflect that.

However, according to the National Institute of Standards and Technology, the cost of inadequate interoperability for U.S. capital facilities during the operation and maintenance phases is estimated at $9 billion US. If you include infrastructure, like bridges and roads, then these costs sky-rocket even further!

Design documents and as-built drawings must be created with a new end in mind.

Engineering and CAD professionals must create their design documents in such a way that the embedded geospatial data can be utilized throughout the infrastructure lifecycle. Design data must be easily integrated with corporate databases so that this information can be used during infrastructure operation and maintenance activities. Engineering GIS can help.

As the original creators of our infrastructure data, I believe engineering and CAD professionals have a responsibility to ensure that this information can be easily integrated throughout the infrastructure lifecycle. To do otherwise, simply contributes to the billions of dollars already wasted due to the lack of interoperability and poor data integration.

The Five Principles of Engineering GIS

Have you ever rummaged through your toolbox looking for that certain tool only to find that you stored it somewhere else? If you have then you know how frustrating and inefficient it can be.

Well, when it comes to CAD and GIS, traditional thinking separates design tools from geospatial tools into different packages. When you’re faced with working in both domains, however, you end up switching back and forth between those packages. This means you also need to pass the data back and forth. The process is error prone and not very efficient.

Engineering GIS combines CAD and GIS capabilities into a single unified toolset. That is, the engineering design, data creation and editing tools of CAD are combined with the database, analysis and spatial data management tools of GIS.

There are five key principles of Engineering GIS:

1. Data passes through a lifecycle. Engineering GIS recognizes that data passes through a lifecycle. For example, when working in the municipal infrastructure domain, data moves through various phases from surveying and mapping, to design and construction, and finally to management. Engineering GIS assumes that the design information will be used in different ways by many people downstream from the engineering design process. Consequently, engineering drawings are topologically correct and “GIS ready” which streamlines the task of incorporating this information into an infrastructure management system and a geospatial database.

2. Access data natively. Engineering GIS recognizes that data comes in many different formats and from many different sources including traditional engineering and GIS environments, spreadsheets and databases, as well as, desktop and web-based sources. However, rather than relying on a data import/export process, Engineering GIS promotes working with the data in its native format. Consequently, data integrity is maintained, data redundancy is reduced and efficiency is improved.

3. Leverage design tools. Engineering GIS leverages CAD and engineering design tools because of their precision and ease of use for data creation and maintenance of engineering design features, as well as, mapping and other geospatial data.

4. Leverage geospatial tools. Engineering GIS leverages GIS tools because of their data oriented capabilities for automated mapping, spatial analysis and management of geospatial databases.

5. Renderings must be accurate. Whether printed to paper or published to the Web, Engineering GIS ensures that drawings and maps are accurately rendered with the point, line and polygon styles, raster and vector overlays, symbology, dimensioning and overall appearance that users expect.

As you can see, with Engineering GIS, you don’t have to choose between CAD and GIS software because both types of tools are available in one place. Together, they create a toolset that simplifies engineering and geospatial data integration.

Until next time...why not take a moment to geoExpress yourself?

CAD and GIS like Milk and Cookies

Milk and cookies - just plain good! There’s something about pairing the crunchy sweetness of cookies with a refreshing glass of milk that not only tastes great but satisfies too. Some things are meant to be together.

I think that CAD and GIS are kind of like that; I think CAD and GIS are meant to be together.

If you are an engineer or a drafting professional, you know all about CAD. You know the value of using CAD for engineering design and drafting; you know that when it comes to producing accurate drawings for construction purposes, CAD is the right tool for the job. In fact, there’s no better tool.

However, as an engineer, you may also have a need to place your designs within a geospatial context; you may need to combine design information with geographic data and you may need to examine your designs using spatial analysis techniques. In fact, attribute data, raster imagery and thematic mapping may help you to better design and visualize your infrastructure projects.

Traditional thinking separates design workflows from geospatial workflows. Consequently, you stick to what you know. With little experience in GIS or little time to learn new technologies, a choice is made; you focus on design and let someone else handle the geospatial stuff.

Unfortunately, this approach results in a disconnect between design departments and GIS departments, and between CAD data and GIS data. Consequently, workflows suffer which compromise efficiency, affect decision making, and impact data accuracy and currency.

However, there is an alternative: a unified approach called Engineering GIS that embraces both engineering design and GIS. Engineering GIS together with an improved understanding of how GIS skills can complement existing design skills can help overcome those workflow challenges and ensure that CAD and geospatial data are integrated in a manner that respects both engineering design and GIS requirements.

CAD and GIS like milk and cookies – just plain good.

Stay tuned as I elaborate on the importance of an Engineering GIS approach in future posts. I’ll also highlight some of the challenges encountered when attempting to integrate design information with geospatial data and I’ll review the key skills that you need in order to take advantage of Engineering GIS.

Until then… remember to geoExpress yourself.