Geographic Information on the Cloud:
Not All Data is Created Equal!
Chad Grismer, PE – Westwood Professional Services
Good quality topographic data and aerial imagery is critical during the planning and design phases of a
project. Decent quality GIS data is typically available for the entire United States and is becoming more
readily available in AutoCAD and InfraWorks. However, not all of it is necessarily suitable for a proposed
project. A wave of high quality GIS data, such as LiDAR and higher resolution aerials, has become
available for the upper Midwest and especially Minnesota. Typically this information is available from
government agencies on the Internet for free, or at a nominal cost. This session will discuss strategies for
acquiring, vetting and utilizing GIS data on the cloud. We will also cover which data sources are
appropriate to use, depending on the phase of the project. Finally, we will discuss some best practices on
how to consume these cloud-based GIS resources in InfraWorks and Civil 3D.
Learning Objectives
At the end of this class, you will be able to:

Learn where and how to acquire GIS data from the cloud

Learn the range of available GIS datasets by comparing aerial and elevation data with differing
qualities

Learn which GIS datasets are appropriate to use based on the phase of the project

Learn best practices to import aerial and elevation datasets into Civil 3D and InfraWorks
About the Speaker
Chad Grismer, PE is a senior project engineer at Westwood Professional Services, working on a variety
of projects in the land development and power industry throughout the US. He specializes in utilizing
information from aerial mapping and GIS datasets and incorporating them into the engineering design
process. He is also interested in developing solutions to share engineering design data so it is valuable
in desktop and mobile GIS systems. Chad had been using Autodesk products for over 20 years and
during his 10 years at Westwood, he has been involved on projects in over 30 states.
Geographic Information on the Cloud: Not All Data is Created Equal!
Looking beyond Google Earth
Google Earth and other web-based mapping applications are terrific resources. These tools are great
ways to quickly learn more about a project without investing a lot of time downloading data. However,
their presence across the web is uneven and not available for every project location. Wouldn’t it be nice
to have GIS data, such as high-resolution LiDAR and aerial photography, available in Civil3D or
InfraWorks? You can start designing a project with high quality data, even before a surveyor sets foot
on the site.
Where do you find this LiDAR and aerial photo data anyway?
Unfortunately, there isn’t a master GIS clearinghouse for the entire Internet. Multiple federal agencies
house GIS data. The same is true at the state level. However, not every state has the same quality of
data online. Some states are definitely better than others. Similarly, some counties and cities have
great resources online, while others are non-existent or require a phone call to the local GIS official.
Luckily for us working on projects in the Upper Midwest, states such as Minnesota, North Dakota, and
Iowa have pretty solid GIS resources readily available online. The best part is the data is typically free!
Google is your friend when finding various GIS datasets across the web. Google terms such as
“Minnesota aerial photo” or “North Dakota LiDAR” and one of the first couple results is typically going to
take you to what you need. However, below are some sources to get you jumpstart your search for GIS,
LiDAR and aerial photo data.
LiDAR aerial photo and other GIS resources
Lidar Resources across the country: http://www.csc.noaa.gov/inventory/
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Geographic Information on the Cloud: Not All Data is Created Equal!
LiDAR resources in the Upper Midwest
Minnesota: http://www.mngeo.state.mn.us/chouse/elevation/lidar.html
Iowa: http://geotree2.geog.uni.edu/lidar/
North Dakota: http://lidar.swc.nd.gov/
Nebraska: http://dnr.nebraska.gov/lidar-2-meter-2009-2012
Wisconsin: http://relief.ersc.wisc.edu/wisconsinview/form.php
Aerial photo resources
High quality Minnesota aerial imagery:
http://www.mngeo.state.mn.us/chouse/wms/wms_image_server_layers.html
NAIP aerials across the country: http://datagateway.nrcs.usda.gov/
A cross-section of additional good-quaility resources
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Geographic Information on the Cloud: Not All Data is Created Equal!
Comparing aerial photo resources
Not all aerial photos are the same – here’s how they stack up against each other. The example below is
an electrical substation. The dimension below is the size of each pixel.
NAIP - 1 meter
Custom Flight – 6 inches
Esri World Imagery - 1 foot
Comparing Aerial photo suitability for a project
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Geographic Information on the Cloud: Not All Data is Created Equal!
There’s stuff above the ground? Wait… What?!?
Most designers are familiar with surfaces generated from the bare earth DTM surface. Your typical
contour map is a representation of this surface. All of the above-ground features -- such as trees,
buildings and power poles -- have been removed from the surface. With the advent of LiDAR, getting
accurate data on these above-ground features is easier than ever!
Below is an example of the same suburaban location. The first one shows the bare earth surface. The
second shows the entire LiDAR point cloud at an oblique angle (brown=bare earth, orange=buildings,
green=vegetation)
Bare Earth Surface - MnGeo DTM (2012)
LiDAR Point Cloud - MnGeo LiDAR (2012)
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Geographic Information on the Cloud: Not All Data is Created Equal!
Comparing elevation resources
At the end of the day, most designers and engineers really care most about the bare-earth DTM surface.
LiDAR is the current gold-standard. However, it isn’t available everywhere in the Upper Midwest and
certainly is not available in many locations across the western United States. If you get stuck using
lesser quality data sources, here’s how they compare. Represented below is a variety of landforms –
highways, rivers, hills, farmland, and residential.
NAIP Aerial 1 meter (2012)
USGS 10 meter
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Geographic Information on the Cloud: Not All Data is Created Equal!
Comparing elevation resources - continued
Intermap 5 Meter
.
Minnehaha County SD LiDAR (2008)
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Geographic Information on the Cloud: Not All Data is Created Equal!
Can I use public elevation data on a project?
The elevation accuracy requirements of a project vary quite widely. A preliminary study might be able to
get by with a lower quality dataset. On the flip side, a professional engineer might not even consider
signing a plan set that used anything less than GPS-collected topo data that was surveyed by his most
trusted crew.
Below are some thoughts based on working on a variety of large-scale energy projects across the
country. A one-sized approach does not fit all projects – please be careful! Your mileage may vary
when considering smaller scale land development projects. Data suitability is highly dependent on the
phase of the project. Don’t be afraid to update your Civil3D existing ground surface as the project
progresses through its life cycle and better data becomes available.
Comparing Lower-quality elevation dataset suitability
Comparing Higher-quality elevation dataset suitability
Using aerial and elevation data in Civil3D and InfraWorks
Autodesk has added some nice GIS features over the years. AutoCAD now has access to Bing aerial
photo imagery. InfraWorks has a tool called Model Builder that allows easy access to Bing aerials and
USGS 10-meter elevation models. These are great ways to jump-start the design process without much
effort. However, many times there are higher-quality data sources available, especially in the Upper
Midwest. Luckily Civil3D and InfraWorks allow you to import your own GIS data sources. Go to
Autodesk University (http://au.autodesk.com/) to find training resources that discuss these topics further.
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