Using LIDAR elevation data from USGS

H.W.Stockman
Dec 28, 2024
This update is acually from 02/25/2025. USGS has changed the web site substantially (several times) since I wrote previous instructions, so I hope this stays relevant. Keep this page open as you play with the real USGS map in another window. On the real USGS site, you can use + and - keys at upper left to zoom, and you can drag the screen with cursor or finger to pan. Please use a real desktop computer or big tablet for the USGS site -- that site is painful on a smartphone.
Not all parts of the USA currently have LIDAR data, but where it exists, the topography is much better defined than in the older photogrammetric surveys. Currently the user interface at the USGS National Map site allows one to access LIDAR, but is rather awkward. The USGS map doesn't tell you where LIDAR is available, but if you zoom into a mile-scale area, LIDAR is quite distinctive --  small stream gullys, individual rocks, ledges and so forth will be visible.

This web page provides a guide to refining the prominence of a peak, with the example of "The Jingle Bells" (35.92803, -115.40994) SW of Las Vegas. From the elevations in images (07) and (08), we get a prominence of 4986'-4681'=305' (+/- 3').

 Click/tap on each small image to view the larger image.  Most screenshots below have written instructions on them. Remember these are just screenshots!

map01
01) Default map is
hillside shading on
the DEM (digital
elevation model),
which is not too
intuitive. The real
USGS map is here.
 map02
02) ...you will probably
want to change
to topo map. NOTE
I have typed coordinates
into upper right dialog
box; hit "enter" after
typing coordinates.
map03
03) To get anything to
show up, you may
have to hit the minus
(-) sign in upper
left corner several
times, then maybe +
 map04
04) I used the right-side
menu to toggle back
to the hillshade DEM
view
map05
05)  I've zoomed in
with +/- buttons on
upper left, and chosen
contours from the menu.
 map06
06)  I have refined
to 1m countours.
map07
07) I use the information
button and pick a
point at the top of
the peak.
 map08
08) Now I pick a point
in the prominence-
defining saddle. This is
a bit tricky, as you
need the "highest low,"
right on the midline.