(Andy Martin to tnm_help@usgs.gov)
    Hi National Map support -

    Is there any way to get the elevations of the contours on the
    National Map 3DEP Elevation - Auto Contours layer ?

    Discussion follows. Appreciate your help.

        Andy Martin
        Tucson Arizona

(Discussion)
    I have some feedback on the 3DEP Elevation - Auto Contours.
    I'm thinking that in areas with LiDAR coverage these contours
    are generated from the LiDAR elevations.
    For example in the first attachment the 3DEP contours show
    much more detail than the contours on the older 7.5 minute
    quad of the same area (second attachment).

    Is there any way for me to get the elevations of these 3DEP
    contours ?

    It would be handy if your map showed these automatically.

    If this is not possible then some sort of user
    query would be helpful.

    I have tried the Spot Elevation and Elevation Profile
    tools. However these seem to reference older elevations
    that do not correspond to the 3DEP contours.

    For example the profile on the first attachment shows
    a steady drop in elevation from west to east.
    This corresponds to the contours on the old 7.5'
    quad.

    However the 3DEP contours (first attachment)
    do not show a steady drop.

    Spot Elevation queries along this profile show
    a similar issue. 




(Reply from USGS National Map Help Desk)
Hello Andy,

Thank you for your feedback regarding The National Map Viewer and 3DEP Elevation layer.

1. Unfortunately, there is no way to label  contours for the 3DEP Elevation Auto Contours.  We are using a set of ESRI web mapping tools and there is no option for us to turn on contour labels.  We wish we could, too

2.  You are correct.  In the areas where we have lidar coverage, the lidar is used as the source for the contours.  That is why there is a different level of detail in some areas compared to others.  As we continue to collect lidar data across the country, you will see contours that resemble the 7.5 minute map contours less and less.

3. User Query/SPOT Elevation/Profile.... You are correct, the SPOT elevations and profiles may differ from the auto contours shown on the map.  The auto contours are based on a higher-resolution Elevation Service that is updated quarterly, so most areas that we have lidar for are reflected.  The SPOT Elevation and Profile tools are based on a lower-resolution elevation model that is about 4 years old, so many of the areas that we have lidar for have not been updated.  I have requested, and will continue to advocate for, the re-generation of the Elevation Model that is used for SPOT Elevations and Profiles.

If you need further assistance please do not hesitate to contact us.  Thank you for contacting the USGS National Map Help Desk!  tnm_help@usgs.gov

Sincerely,