Get Your Head in the Clouds

Geospatial applications are renowned devourers of information. As new technologies for capturing data are developed, the geospatial applications soon follow. It makes sense as we try to find better and cheaper methods of modeling our world. One of these technologies is LIDAR (Light Detection And Ranging). LIDAR is becoming a common remote sensing technique. It sends out and measures the return of laser pulses to determine distances (as well as other information) in 3 dimensions to essentially generate a 3D view of the scanners environment. The resulting data is a very large group, or cloud of X, Y and Z values (along with other descriptive information depending on the equipment and technique). These point clouds have required specialized software to view and capture information.
Now, subscription AutoCAD Map 3D and Civil 3D users have some new tools available to work with these point clouds. The new Subscription Advantage Packs include tools for viewing and classifying Point Clouds. This can be incredibly useful to geospatial users. At a large private electric utility I used to work for, we used LIDAR as a method to survey electric transmission lines and surrounding vegetation. We were looking for trees that were growing into the lines and cause potential outages.

After installing the new Subscription Advantage packs in AutoCAD Map 3D, some new options become available. In the Task Pane’s Display Manager Tab, there is a new option in the Data menu – “Add Point Cloud Data.” Selecting this option opens a file select dialog prompting for an ISD file – a Point Cloud index, or data store file. You create the index from the new Point Cloud Manager.

 
Another new option is in the Tools menu – “Create Point Cloud Index.” This option opens the Point Cloud Manager.
From the Point Cloud Manager, we can add LIDAR data files to create a Point Cloud data store, merge them into groups, set coordinate systems, use filters to classify, create elevation ranges and even create spatial filters.
 

Adding the Point Cloud Data will create an entry in the Display Manager tab, and add a new Point Cloud ribbon giving us tools for stylization, exporting and creating surfaces. 

Keep in mind, these data sets are big, and will tax your system resources, so be prepared.
So, get your head in the clouds and check it out. The view is great.

Happy GIS Day! Here’s some Arizona GIS Data Sites

• Today is National GIS Day!

CADsoft Consulting’s CAD Camp 2009 is well underway.  We had a very successful Architectural/BIM day yesterday, and the Civil day is in full swing. Tomorrow will be the Geospatial Day (so it doesn’t interfere with any GIS Day activities). This morning we’ve had a presentation from Autodesk’s Civil 3D maven, Lucy Kuhns, and our own Ron Coulliard is doing a workshop on grading as I type. During Lucy’s presentation, I was asked about local Arizona GIS data, so I promides to share some of the sites I use/am aware of. The list is by no means exhaustive, and there’s some dupplication within the sites, but here you go anyway. I’ll continue to identify sites I run across in the future. If you’ve got some good ones you want to share, add them to the comments or email to me and I’ll add them to the list.

GIS Data Sites for Arizona

Arizona State Cartographer’s Office 
They maintain the Arizona GeoServer, with aerial photos and statewide features served through web mapping services (WMS) and web feature services (WFS). They also maintin links to other data sources throughout the state

The AGIC (Arizona Geographic Information Council) GeoData Portal
AGIC is a state sponsored group working with GIS across the state. They sponsor an annual GIS educational conference every year. We just finished the 2009 conference in Tucson. There was great attendance. I presented 3 hands on worksops this year.  They have County boundaries, tribal boundaries, cities, wilderness areas, political boundaries, voting districts, school districts, census information, environmental and natural resource data, interstates and roads

US Fish and Wildlife
USFW maintains larger scale data sets covering National Wetlands Inventory and area boundaries

U of A Library
The U of A Libraries maintains the Arizona Electronic Atlas and the Arizona Regional Image Archive (ARIA) as well as links to other data sites

ASU
The ASU Libraries also has spatial data and links available

ADEQ
Arizona Department of Environmental Quality (ADEQ) has water quality data, surface, drinking and groundwater

Local division sites

Maricopa County
The County Assessor’s Office GIS Department maintains data for the county including parcels, detailed topographic data, floodplains, and survey network.

Pima County
Pima County is really one of the long runners in GIS. They have had data available for as long as anyone in the state. They maintain over 273 data layers in ESRI shape files as well as landbase section maps in AutoCAD format.

City of Phoenix
Phoenix has an extensive collection of GIS data.  They have Engineering Quarter-Section maps in DXF format CAD files

Nationally-based sites

US Forest Service

FEMA
The Federal Emergency Management Agency maintains flood hazard data sets which are available as GIS data sets or through a Web Mapping Service (WMS) 

NSGIC
The National States Geographic Information Council maintains an inventory of data and its currency in the Ramona GIS Inventory. Arizona’s page is here:

Natural Resources Conservation Service (NRCS)
The NRCS maintains the Soil Data Mart with soil data available by state. They also collect other data such as water supply and snowpack

United States Geological Servey (USGS)
The USGS maintains large scale data sets for the US. They have digitial orthoquads and photos, land cover, elevation model and other data sets.

US Census Bureau
The Census maintains census and popluation data for the US

United States Department of Agriculture

USDA has Forest Coverage

Geography Network
The Geography Network maintains various spatial data sets for the US

ESRI Geoportal Extension
ESRI has a beta site with downloadable GIS data

National Center for Atmospheric Research
Atmospheric data for the US

New Mexico

Lucy Kuhns mentioned the New Mexico Resource GIS program site. Here’s the link:
http://rgis.unm.edu/

Losing Your Religion: Interoperability with AutoCAD Map 3D and ESRI

I’ve been speaking at conferences for several years about CAD and GIS interoperability. It’s one of those topics where there’s a lot of interest and a lot of misinformation. Or at least, it seems to be much more difficult than it really is. I’ve been moving data between both systems for years, with very few real challenges. What I’ve found, is that the real issue is not the technical aspect of moving data back and forth, but the differences in how the software is generally used. AutoCAD (and other CAD systems) are primarily used for doing design work, and GIS (ostensibly ESRI, but it could be any GIS system) is primarily used for managing as-built facilities and systems. The real challenges are working between the design and as-built management processes. In other words, the issue isn’t CAD to GIS, the issue is Design to As-Built.

I’m going to make several blogs here in a series of the issues and some methods to make the process easier. This first post, I’m going to discuss the a bit about the similarities in the technologies. Following that, I’ll be posting on the differences, barriers, myths, and other issues involved.

Both AutoCAD and ESRI are built on basic primitive elements that are combined to create representations of real objects. Both systems include:

Points - a representation of a single location. It could represent a physical object such as a pole, manhole or brass cap in the ground, or it could be a non-physical point, such as a crime scene location or the corner of a property line. In any case, the systems both record a coordinate consisting of an X and a Y and possible a Z (if elevations are being included). The X and Y value could represent any projection or coordinate system, such as degrees of latitude and longitude or northings and eastings from a state plane.

Lines – a representation of of a connected set of coordinate pairs. Every line is going to have a start point defined by X, Y and/or Z, and and end point defined by an X, Y and/or Z. It could represent the centerline of a road, the edge of a building, or a buried pipe.

The line may be defined the system by coordinate pairs, such as point A and point B, or it could have the actual coordinate values in the line definition, such as this example from AutoCAD (a listing of a line – the start point is the set of parenthesis with the 10 X Y Z, and the end point is 11 X Y Z):

In some cases, for example, ESRI, the actual coordinates of the line are stored within an object “envelope”, which is a rectagle enclosing the object.

 Polygons – a representation of an area. It could be a representation of a parcel, a building footprint, or an animal migratory zone. It is defined by lines and so by a series of bounding coordinates. Generally, in vector systems (save that discussion for another time), polygons are defined by their boundaries. They could be defined by groups of lines, or it could have the coordinate values built into the definition, simlar to the lines (as shown above).

In ESRI, the coordinate pairs are contained in an envelope bounding the entire object:

Attributes -  data associated with an object. Associated data could be an identification number, a name, a description of the object, the color, size, diameter, etc. This is what turns a simple point, line or polygon into a representation of a fire hydrant, electric line or county. Attributes may be stored and linked to the object in a myriad of methods. It could be based on a common identifier stored in the object definition and the attribute list, as in a primary-foreign key relationship, or the definition of the object may be created to include certain atribute sets intrinsically. In some cases there may be a mixture of methods. For example, in AutoCAD, objects have intrinsic attributes (such as blocks attributes), extended entity data (attribute values associted to an individual object), or object data (data tables stored internally in the drawing and linked to objects). Additionally, both systems include methods to link objects to externally associated databases to extens the attributes of an object.

Understanding these similarities is key to understanding how to integrate these two systems. The next post, I’ll discuss the primary differences between the two.

Breaking Out of the DWG

Professionally, I’ve always been square on the fence between CAD and GIS. The funny thing is that GIS folks always call me a CAD guy, and the CAD guys always call me a GIS guy. Personally, I’ve always believed in using the right tool for the job, regardless of the technology. The best part for me is that I learn from both technologies and apply them wherever it fits. One of those “learnings” has been to break free from the DWG in AutoCAD Map.

Traditionally, when working in AutoCAD, we work in a drawing. The drawing maintains the model as well as any associated annotation, labeling, details, etc. At most we’ll have a group of drawing files, and some external references to share drawings. It’s much like using Word. We work in documents.

Traditionally, working in a GIS is a bit of a different model. While you have views, or map documents (depending on the particular flavor of GIS) your documents are really little more than a collection of links to data with some instructions on symbolizing the data. It really is more like working in a database, like Access, than in a document.
Both approaches provide benefits, so why not mix them? AutoCAD Map 3D allows me to bridge the gap between technologies. I can use my current drawing file as a pointer to various data sets, while having additional drawing information in my drawing file. For example, I can have my model (the actual drawing representation, whether it be a design of a road, or a city water system) linked from external data sources, and have multiple drawing sheets, complete with one or more title blocks in my current drawing. It allows me to have specific views, sheets or plans with project-specific data and take advantage of permanent data stores that are dynamic and updated each time I open them.

This allows me to use my enterprise GIS as part of my design tools without having to go through a conversion process. The great part is that it doesn’t really matter what my data source is. I can use other drawings through the attach and query tools, as well as Feature Data Objects (FDO) connectors to systems such as ArcSDE, Oracle or MySQL. I’ll blog more on that GIS-Design integration another time. The point being, is that the individual drawing can lose it’s importance and become essentially a snapshot of your model.

When using drawings as your data source, you can either use the ribbon or the Task Pane (as well as the Classic Menus). On the Ribbon, Attach is right on the Data Panel on the Home Ribbon for both task and tool-based workspaces. The Map Explorer tab in the Task Pane provides a visual of the drawings attached – to access the commands right click on drawings.

FDO data sources can be connected using Connect on the Data Panel in the Home Ribbon as well (next door to the Attach commands), or from the data button at the top of the Task Pane.

The short story is that you don’t have to be a slave to your DWG file, and treating your DWG as a view to your model, you have some real power to take advantage of a whole new range of possibilities. The great part is that this is not new technology (the FDO process is relatively recent). Map has incorporated this capability since it was acquired.

So, unleash the shackles and get connected.

Welcome to CADsoft Consulting’s Geospatial blog!

We’re proud to announce the launch of the newest blog in the CADsoft family – Neatline — a Geospatial Conversation, hosted by Rick Chappell.