Resources More Useful Links
Supplemental Site Inspection and Analysis Tools
A number of online resources can be used to prepare for, enhance, and extend the
inspection and analysis of a project site. The following resource links are provided
as a convenience and they represent some good examples of what's available today:
[If you have a site inspection/analysis resource recommendation for this page,
Google Earth Pro
Access to online satellite and aerial imagery has been available via the free standard
version of Google Earth for over a decade now; however, starting in January 2016, the
advanced capabilities of
Google Earth Pro are also available for free (if a license key is requested during installation, enter "GEPFREE"). If you have never
seen this impressive virtual site inspection tool, then you can't possibly imagine
all that you have been missing. To get started, install and run Google Earth Pro, enter a project address in the Search field then click the "Search"
An Introduction to Google Earth Pro (PDF) and
Google Earth User Guide (PDF) for detailed usage instructions.
Users of AGTEK's
can import a
saved image from Google Earth and display it as a background layer in their AGTEK
project file (see this AGTEK
training video for step-by-step instructions).
Analytic Accessories for Google Earth (Install Google Earth Before Using These):
AGTEK Color Cut-Fill Map Overlay
Users of AGTEK's
3D, and Earthwork
4D products can export a plan-view color cut-fill map (and/or corresponding
PDF plan sheets) to a KMZ file which displays as an overlay layer in Google Earth
(see a PDF with
brief instructions or watch a detailed AGTEK training video for
Earthwork 4D). The KMZ export option is not available to AGTEK
Earthwork 3D users
but they can print a cut-fill map to PDF, convert the PDF to JPG then
upload and overlay
the JPG image in Google Earth.
Topographic Contour Map Overlay
Google Earth lacks a function to display elevation contours but a workaround is
to overlay a third-party topographic contour map. For a seamless overlay of
combined USGS "topo quads" for all U.S. states (and most U.S. territories), go to the
Earth Point Topo Maps on Google Earth page then click the "View
on Google Earth" button to open the EarthPointTopoMap_170102.kml
file in Google Earth (a resulting Earth Point Topo Map subfolder will be
located in Google Earth's Temporary Places folder but it can be moved
to the My Places folder for future use). For more control and
options you will prefer to use the
USGS topoView portal, which provides an intuitive map-based graphical
interface for the location and selection of individual topo quads with a choice
of topo quad edition (recent and historic) and download format--KMZ for Google
Earth and geo-referenced layered PDF/TIFF options (download a KMZ map file then
double-click it to view the topo map in Google Earth). Other topo map overlay
options include utilities such as
Earth Survey QUADS and
Google Earth Library. See these
interpretation resources if you're not familiar with reading USGS topo maps.
Interactive Soil Map Overlay
Are you unfamiliar with a site's
soils and lacking a site-specific geotechnical report? Go to the California
Soil Resource Lab's
SoilWeb Apps page then click the "SoilWeb Earth" link to
open the SoilWeb.kmz file in Google Earth (a resulting SoilWeb subfolder
will be located in Google Earth's Temporary Places folder but it can
be moved to the My Places folder for future use). This soil mapping
tool is based on
USDA-NRCS soil survey data, with coverage for about 95% of the United States.
The map displays soil types in the area of interest with supporting descriptions
and, depending on location, additional details on engineering properties, vegetation,
etc. may also be included.
State Geologic Map Overlay
The USGS Mineral Resources page provides
Geologic Maps for the United States and KML/KMZ maps are available for all
states (except Alaska and Hawaii). Click the desired state kml/kmz file link
to open the map in Google Earth (a resulting state Geologic Units subfolder
will be located in Google Earth's Temporary Places folder but it can
be moved to the My Places folder for future use). The maps represent
lithology via color filling corresponding to this
interactive color legend.
Wetlands Data Map Overlay
The U.S. Fish and Wildlife Service provides a KML
Wetlands Data Map for the United States. Click the Wetlands-Data.kml
file link to open the map in Google Earth (a resulting FWS Wetlands & Riparian
Data subfolder will be located in Google Earth's Temporary Places
folder but it can be moved to the My Places folder for future use).
State Plane Coordinate System Zone Map Overlay
This free utility can be used to identify the SPCS zone for any U.S. site and
the borders between adjacent SPCS zones; it also includes a Lat/Long-to-SPCS converter.
Go to the Earth Survey
SPCS83 for Google Earth page then click the "SPCGE" download
link to open the spcge.kml file in Google Earth (a resulting SPCS833
subfolder will be located in Google Earth's Temporary Places folder but
it can be moved to the My Places folder for future use; in order to see the
zone boundaries, be sure to check the Zone Finder subfolder).
SPCS zone identification and Lat-Long/SPCS conversions can also be done using the free browser-based
NGS Coordinate Conversion and Transformation Tool (NCAT) (a 15-minute
training video covers the basics of using the NCAT tool).
Locate NGS Survey Control Points
DSWorld is a free PC-based utility that makes it easy to search for NGS (National Geodetic Survey)
control points located near any U.S. site, with the results plotted in Google Earth (a 47-minute
training video covers the features and functions of DSWorld). An alternate NGS control point locator is the
Earth Survey NGSCS utility.
AGTEK-Readable 3D Topo Contours
Although the Topographic Contour Map Overlay options for Google Earth (see above) are used
only for a visual representation of site topography and the overlay contours cannot be imported and used
for surface modeling in AGTEK, there are a number of sources for 3D vector topo contours that can be used for surface
modeling in AGTEK. [Note: Don't expect survey-quality horizontal and vertical accuracy from these
sources (the 3D contours are typically sourced from the USGS for U.S.-located sites) but the resulting topo data may be a "good
enough" starting point for preliminary site analysis and planning uses.]
SITEOPS Topo Lite
The ability to download a DWG file containing 3D contours (and an aerial image) for any U.S.
parcel was a very useful feature of the formerly free browser-based SITEOPS® Topo Lite
service from Blueridge Analytics. Unfortunately, following Bentley Systems' acquisition of Blueridge
Analytics, the free SITEOPS Topo Lite service was discontinued in 2017. Equivalent (and expanded)
functionality is now available via the Topo Import module of Bentley's subscription-based
SITEOPS service but the cost may be prohibitive for infrequent users. The spatial reference
for SITEOPS' topo data is feet in state plane zone coordinates.
($249, requires AutoCAD Full 2010+) provides a number of CAD/Google Earth data-interchange functions, including
the ability to capture and import a Google Earth terrain mesh (in user-defined units) and generate 3D contours
from the terrain mesh.
The free browser-based
Cadmapper service allows users to download a DXF file containing 3D contours and 2D roadway alignments
for any site location. The spatial reference for Cadmapper's topo data is meters in UTM zone coordinates,
which is an inconvenience for most U.S. users.
USGS TNM Download
USGS Topo Map GIS Data corresponds to the USGS topo maps discussed under Topographic Contour Map
Overlay options for Google Earth (see above) but the GIS (Geographic Information System) data equivalents
contain 3D topo contours, newer data sets and many additional data layers (click here for an overview with training video links). The GIS map data is not directly readable
by AGTEK because it is provided in a ESRI geodatabase (GDB) format; however, the GDB files can be read by
(a free open-source GIS program) and the 3D topo contours can then be exported from QGIS to an AGTEK-readable format such
as DXF. [Tip: Layered vector GeoPDF topo maps can also be downloaded from the same TNM site and these can be directly imported by AGTEK. Although the vector GeoPDF maps contain 2D topo contours, the contours can be quickly elevated in AGTEK and this will probably be an easier approach for most AGTEK users.]
There are simply too many potentially useful resources to list, but here are a few
that may be worth a look (some of the Google Earth accessories described above tap their
data/functions from the NGS and USGS resources below) ...