Archived GIS Snippets
Published in 2013
Permanent URL
Users offer 10 security tips to IT staff
by susan miller
The opinion many IT security people have of end users runs a narrow gamut, somewhere between lack of trust and healthy skepticism, according to a survey commissioned by Akamai Technologies. A commentary on the poll in GCN’s CyberEye blog sparked a number of comments from readers, including several recommendations on how to maintain this uneasy truce. Here’s a roundup.
1. Make it usable: If a system is secure but does not allow getting the work done, people will do an end-run around the policy. continued…
first published week of: 12/02/2013
Permanent URL
USGS Redesigned the Topo Map
USGS has redesigned their PDF topo maps! Just released are complete map sets for Tennessee (694 maps) and Kentucky (671 maps) with more states coming soon (Alaska and Hawaii).
These maps are beautiful. If you want to see a sample we have Mammoth Cave, Kentucky unzipped and ready for you to download – but be warned that it is a really big file (30 megs) and will take quite a while to download – but well worth the wait…
If you have Adobe Reader or equivalent software, click here, get the download started, go for coffee, come back to a great map. Be sure to zoom in to see the great detail.
first published week of: 05/20/2013
Permanent URL
USGS Release: Buckeye Quads Released
Figure showing available PLSS areas on the new Ohio US Topo map. Note: "US Topo maps are not legal documents. The PLSS information shown on these maps is for general reference purposes only, and should not be used to determine legal boundaries or land ownership. The Bureau of Land Management (BLM) is the authoritative source for PLSS information at the federal level, and the US Topo representation is derived from BLM GIS data files. The management of these data is not completely uniform throughout the country.".
The USGS, in cooperation with other Federal agencies, has posted new Ohio US Topo quadrangles (748 maps) which include partial Public Land Survey System (PLSS). Ohio is the first state east of the Mississippi River to have PLSS data added to US Topo maps, joining Wyoming and Colorado in the west.
"It is great to have these 748 updated US Topo maps for our state available online at no charge," said Charley Hickman, the Geospatial Liaison for Ohio. "We appreciate the continuing improvements in this product, including the availability of PLSS township, range, and section information."
The PLSS is a way of subdividing and describing land in the United States. All lands in the public domain are subject to subdivision by this rectangular system of surveys, which is regulated by the U.S. Department of the Interior. Other selected states will begin getting PLSS map data during the next respective revision cycle.
The new design for US Topo maps improves readability of maps for online and printed use, while retaining the look and feel of the traditional USGS topo map. Map symbols are easy to read when the digital aerial photograph layer imagery is turned on.
Other re-design enhancements and new features:
- New shaded relief layer for enhanced view of the terrain
- Military installation boundaries, post offices and cemeteries
- New road classification
- A slight screening (transparency) has been applied to some features to enhance visibility of multiple competing layers
- New PDF legend attachment
- Metadata formatted to support multiple browsers
US Topo maps are created from geographic datasets in The National Map, and deliver visible content such as high-resolution aerial photography, which was not available on older paper-based topographic maps. The new US Topo maps provide modern technical advantages that support wider and faster public distribution and on-screen geographic analysis tools for users.
The new digital topographic maps are PDF documents with geospatial extensions (GeoPDF®) image software format and may be viewed using Adobe Reader, available as a no-cost download.
These new quads replace the first edition US Topo maps for Ohio. The replaced maps will be added to the USGS Historical Topographic Map Collection and are also available for free download from The National Map and the USGS Map Locator & Downloader website.
US Topo maps are updated every three years. The initial round of the 48 conterminous state coverage was completed in September of 2012. Hawaii and Puerto Rico maps have recently been added. More than 400 new US Topo maps for Alaska have been added to the USGS Map Locator & Downloader, but will take several years to complete.
For more information, go to: http://nationalmap.gov/ustopo/
first published week of: 11/18/2013
Permanent URL
USGS Topo Data on the Go
USGS The National Map Topographic Data are now available on mobile devices that are using the Android or iOS operating system
Android and iPhone users can now use their mobile devices as digital topo maps, leveraging USGS maps together with the power of GPS to zoom in on their precise location while hiking, biking, running, or any other activity that benefits from precision navigation. The type of data that are available includes USGS imagery and topographic maps from The National Map, as well as road and contour layers.
Currently, two Android applications are using USGS data, OruxMaps (http://www.oruxmaps.com/index_en.html) and AlpineQuest (http://alpinequest.psyberia.net/). These apps include USGS services in the list of available online maps.
For users that may be navigating in an area that is outside of cell phone coverage, Mobile Atlas Creator (http://mobac.sourceforge.net/) is allowing users of this desktop application to build small "mobile atlases" with USGS data. These "mobile atlases" can be built over any area of interest at multiple scales, and when completed, the small file is moved to the phone. The "mobile atlases" enable GPS applications on both iPhone and Android mobile devices. By storing this small amount of data on the phone, these "mobile atlases" ensure the topographic data is available even when cell coverage is not.
Users of mobile devices can use USGS data on their GPS-enabled phones to track their adventure or workout. This capability is new, and promises to increase awareness and use of USGS data and services, as well as increase demand for US Topos.
To use TNM data on your Android device:
- Install either OruxMaps or AlpineQuest via Google Play App Store.
- USGS TNM data is available through these two applications as a dynamic, online layer.
- Switch map sources to view either TNM Topo or Satellite data through the application.
- OruxMaps manual available online in PDF format.
- More information on Alpine Quest is available online.
To use TNM data on your iOS device:
- Install Galileo on your iPhone or iPad via iTunes App Store.
- Build offline map file(s) on MOBAC (instructions below).
- Move files to iPad or iPhone.
first published week of: 05/06/2013
Permanent URL
Using Open Source GIS tools for spatial data - QGIS, GDAL and Python
by steven citron-Pousty
This is the second in my new spatial application and data blog series. Our goal in this series is to show all the different ways we can create applications and run standard servers with geospatial data. I chose an area around Boulder Creek, CA in Santa Cruz County to obtain data to be used in this series.
In the first blog in this series I looked at how to get spatial data, what format it would probably come in, and how to deal with it's projection. Now that we have the data we are going to visualize it a bit and then do some programmatic analysis and re-projecting.
Now that we have all this great data let's talk about how to look at and process it. The typical GIS analyst will use a desktop application to get started with their data, do analysis, and make PDF or printed maps. The best and most active cross-platform FOSS GIS desktop software is QGIS. With QGIS you can look at all the shape files we downloaded and do processing on them. We will use QGIS throughout this blog series.
Today I am only going to show the bare minimum needed to do our work. If you want to learn more there are plenty of good tutorials and documentation. continued…
first published week of: 03/11/2013
Permanent URL
Using PHP/MySQL with Google Maps
by Ben Appleton, Google Geo Team
This tutorial is intended for developers who are familiar with PHP/MySQL, and want to learn how to use Google Maps with a MySQL database. After completing this tutorial, you will have a Google Map based off a database of places. The map will differentiate between two types of places—restaurants and bars—by giving their markers distinguishing icons. An info window with name and address information will display above a marker when clicked.
The tutorial is broken up into the following steps:
Creating the Table
When you create the MySQL table, you want to pay particular
attention to the lat
and lng
attributes.
With the current zoom capabilities of Google Maps, you should only
need 6 digits of precision after the decimal. To keep the storage
space required for your table at a minimum, you can specify that the
lat
and lng
attributes are floats of size
(10,6). That will let the fields store 6 digits after the decimal,
plus up to 4 digits before the decimal, e.g. -123.456789 degrees.
Your table should also have an id
attribute to serve as
the primary key, and a type
attribute to distinguish
between restaurants and bars. continued…
first published week of: 12/16/2013