USGS TopoView – The USGS seems to be moving fast to improve its on-line services, and the new (as of mid-2015) TopoView is the latest of several USGS digital map search, visualization and exploration tools. Like the earlier USGS Map Locator and Historical Topographic Map Explorer sites, TopoView serves up a full range of digitized paper maps, but in a more comprehensive interface that makes it easier to select maps and download them in a wider variety of digital formats (including geotiff). Unlike the Historical Topographic Map Viewer, which is a great visualization tool, TopoView seems to be more focused on the search and data access side of the equation. My guess is that it will eventually replace the USGS Map Locator site

USGS Historical Topographic Map Explorer – This is a collaboration between the USGS and ESRI to bring the USGS’s collection of historical topographic maps to the web in an interactive environment. This site is focused on visualization and gives you the ability to overlay historical maps on current map data to help visualize changes over time. It’s a great tool, very well done, and the site is a great place to get lost in the topographic history of the United States

USGS Map Locator – Need a map? The US Geological Survey now makes most of its maps available on-line as free downloads in GeoPDF format. The new US Topo series maps have replaced the traditional old 1;24,000 topo quad sheets, but you can still search for and download the older map coverage for most areas. A great service!

TerraGo Technologies – OK, so you’ve downloaded your free PDF maps from the USGS Map Locator site. Now what? To make full use of them you’ll need a free Adobe Reader plug-in called the TerraGo Toolbar

PDFMaps – But wait – what if you want to view and use your GeoPDF maps on your iPhone, iPad or Android device? For that you’ll need an app named PDFMaps from Avenza Systems

Army Geospatial Center – The US Army Corps of Engineers may not like the fact that it is ‘saddled’ with the geospatial mission, but they have always maintained a strong core of expertise in what is today called the Army Geospatial Center.  This entity dates as far back as WWII and previously was known as the Engineer Topographic Laboratory and the Topographic Engineering Center. As an active duty Topographer the predecessors to the Army Geospatial Center often served as a ‘lifeboat’, providing the critical support, technology and expertise to solve many of the tough technical issues we faced. A great organization led by good people

GPS – The US Global Positioning System (Navstar) has revolutionized worldwide location services in ways its developers could never have imagined.  Other competitors have emerged – the Russians (GLONASS), Chinese (Beidu) and the European Union (Galileo) now offer their own space-based positioning services, but the US GPS system remains the world’s gold standard in terms of coverage, availability, system stability and accuracy

ArcGIS.com – ArcGIS.com is ESRI’s web map content development and delivery environment. In the past few years ESRI has come on strong in the arena of ‘web GIS’, not just content delivery, but robust content development and mobile device services all through a web-pure interface. ArcGIS Online is a ‘cloud service’; everything is hosted on-line and it works amazingly well

QGIS – Does ESRI have any real competition?  Yes!  At this point QGIS is just a terrier snapping at ESRI’s ankles, but the desktop software is surprisingly robust, feature rich, mature and well supported by the user community. Plus, it’s free!

GRASS – Before there was QGIS or ArcGIS there was GRASS. GRASS (Geographic Resources Analysis Support System) was the first open source GIS system available to the general public. It was originally developed in 1982 by the US Army Corps of Engineers for use in land management activities on properties the Corps controlled. Very quickly the Corps realized that supporting and upgrading software was not something they wanted to get into, so responsibility for maintaining and upgrading the code was taken over by Baylor University. The software has seen steady (if slow) updates and major releases come about once a year. Today the software is managed and maintained by the Open Source Geospatial Foundation

ERDAS Imagine – GIS folks today get all giddy about the very recent upgrades to ESRI’s ArcGIS for Desktop imagery handling and analysis capabilities. Well, where ESRI is today ERDAS was 20 years ago. ERDAS used to be a privately held company headquartered in Atlanta and headed up by a talented (and very personable) buy named Laurie Jordan. Jordan had done some graduate work on the use of digital multispectral Landsat imagery for earth resource analysis and turned that research into a company called ERDAS (which originally stood for Earth Resources Data Analysis System). ERDAS‘s flagship product was ERDAS Imagine and it is a raster geospatial information system designed for handling and analyzing large volumes of imagery data. About 15 years ago Jordan sold ERDAS to Leica Geosystems and all but disappeared for a time. Since then ERDAS has been kicked around a bit in the marketplace. Leica sold it off to Intergraph, which then became part of Hexagon. Sadly it no longer seems to have the market share or visibility it once had. The US Army has been using ERDAS software since 1989 and ERDAS Imagine became the core of the Army’s first widely fielded GIS system – the Multi-Spectral Imagery Processor (MSIP) and was then incorporated into the Digital Topographic Support System (DTSS). Interestingly, about five years ago ESRI upgraded its desktop software’s ability to handle, process and analyze raster imagery data. The improvements were sudden and dramatic. It was soon revealed that Laurie Jordan had been coaxed out of retirement by ESRI’s founder Jack Dangermond and put in charge of ESRI’s new raster product development group. Jordan convinced some of the talent from his old company to follow him over to ESRI and now ESRI offers an almost seamless integration of vector and raster analysis capabilities

NOAA On-line Magnetic Declination Calculator – Need to calculate the magnetic declination for the area you are working in?  Here’s the site that can do it for you