Arizona Topo: Points of interest WAY off

[desertfish11]

I just downloaded Basecamp and then loaded the Arizona Topo map from this site. The interface works fine, and many of the summits of major mountains are marked correctly on the topo, but I know some of the features in the Santa Catalina Mountains north of Tucson (such as Prominent Point) well enough to see that the points of interest for many that I know of are completely wrong. By "completely" I mean off by like a mile. I suspect this issue is systemic and applies across the whole state because I looked in other regions and found funny data.

Is this an issue anybody else has had with this map? Can I avoid having these faulty points displayed if I want to just work on my own set of waypoints? Is there a fix for this, because I really would like to have an accurate set of interesting points to reference on my adventures.

[-Oz-]

This is the first I've heard of the points being that far off.  With the number of downloads it is odd that this would be the first time.  The points come from the USGS GNIS system.

If you can give a couple specific examples I can do some checking because if it is systemic across the whole state the solution should be relatively easy.

There is nothing you can do to fix it because they are built in to the map data itself.

[Boyd]

Although you can't change the POI's yourself, you can check them against the GNIS data yourself. Go to the National Map Viewer here: http://viewer.nationalmap.gov/viewer/

Zoom in on your area of interest. In the left pane of the window under Base Data Layers, click the check box next to Geographic Names (GNIS) and click the + box to confirm that the data you want is checked. You can also check some of the other boxes to show other features on the map such as roads or elevation contours.

This will show you the GNIS data that should have been used to create the map. If it matches the map you downloaded, then there must be a disconnect between where the USGS thinks things are located and your expectations.

[Seldom]

Although you can't change the POI's yourself, you can check them against the GNIS data yourself. Go to the National Map Viewer here: http://viewer.nationalmap.gov/viewer/

Nice check.  Delicate Arch, in Arches is .29 miles further east of the imagery.  Angel's Landing, in Zion is 347 feet west of where it shows on imagery.

[desertfish11]

Here are some hard numbers on what I've observed:
GNIS marked Prominent Point at N32 21.872 W110 54.554 elev4740
I mark Prominent Point at N32 21.931 W110 53.800 elev6600
Separation: .7mi at 264.5deg

GNIS marked Pontatoc Ridge at N32 21.004 W110 52.822
I mark Pontatoc Ridge at N32 20.696 W110 53.195
Separation: .5mi at 44.6deg

GNIS marked Rincon at N33 09.221 W111 06.724 elev2723
I mark Rincon at N33 08.968 W111 07.115 elev3810
Separation: .5mi at 52.4deg

*all separations measured from my mark to the GNIS mark

This will show you the GNIS data that should have been used to create the map. If it matches the map you downloaded, then there must be a disconnect between where the USGS thinks things are located and your expectations.

I found that the coordinates and comparison to imagery match on Basecamp with Arizona topo and on the Mapviewer. However, note that I chose these locations to compare because I have either gone to them or have knowledge from independent sources on how these features are identified. Also note the incredible error here, on average about a half mile! The elevation change should show you that these features (all high-points) were totally wrong by the GNIS account.

As far as what to do, I guess I can't trust the POI's. I wish they could be removed from the map I'm about to load onto my new eTrex.

[Indrid Cold]

Here are some hard numbers on what I've observed:
GNIS marked Prominent Point at N32 21.872 W110 54.554 elev4740
I mark Prominent Point at N32 21.931 W110 53.800 elev6600
Separation: .7mi at 264.5deg

GNIS marked Pontatoc Ridge at N32 21.004 W110 52.822
I mark Pontatoc Ridge at N32 20.696 W110 53.195
Separation: .5mi at 44.6deg

GNIS marked Rincon at N33 09.221 W111 06.724 elev2723
I mark Rincon at N33 08.968 W111 07.115 elev3810
Separation: .5mi at 52.4deg

Prominent Point
Pontatoc Ridge
looks like the DMS format digits are being displayed as MinDec without any conversion

Couldn't check Rincon as there were several, need more info there.

[Boyd]

So - if I understand what you're saying desertfish11 - the USGS doesn't know where these places really are? Where do the printed USGS 24k topo maps show these locations? Are they also wrong?

If that's the case, I don't see how anyone could make a map with correct data, since we rely on the USGS to provide that.

[desertfish11]

I just looked at the printed version of the USGS maps, and they put a nice x on top of the feature I know is called Prominent point. This feature has an elevation of 6628 ft according to the printed map, which is correct. They didn't label it prominent point and they also have no mark for prominent point where it is marked as a POI in the Arizona Topo map. I am saying that some of the POI's are off in this topo map, while others (like Finger Rock which is right next to Prominent Point) are correct in both USGS printed and Arizona Topo.

[maps4gps]

None of the major Federal databases (GNIS, NHD, NED, TIGER) which we use to create
maps was  funded nor constructed for the purpose of recreating an existing map.
The purpose of GNIS was to document name usage in the USA.
Phase 1 was done 3 to 4 decades ago by digitizing the names used on the printed
USGS 24k topos.  It was all done manually and eventually entered into a main-frame
database via 'dumb' terminals.

I will not go into the history of the project as I observed it in Reston beginning
in 1982.  I actually did; however, my reply from two hours ago did not get uploaded
properly.

The 'x' on the printed topo indicates a spot elevation for which the feature name was
not known.  Indrid's post refering to GNIS indicates the feature was added later from
a county map published by the State DOT.  I would guess the location was incorrect
and was so entered into GNIS.

A ridge is a long narrow area feature.  Where the name was placed on the printed map
and what coordinate was recorded for it is variable.  I did not check it out; however,
if the coordinates are somewhere along the ridge, they are acceptable. 

IMHO there are way too many bad locations in GNIS even considering there are over two
million features in the database.  I suspect it is much easier to obtain funding to add
additional features than to correct the locations of 30+ year old data.

Adjusting coordinates for numerous feature types has been on my 'to do' list for over
three years.  There are no more minutes in my day than anyone elses and With fewer people
creating/updating mapsets and by trying to fill the gaps means for everything I work on
there will not be time for something else.

Boyd - I am getting more and more fustrated in trying to create a top quality mapset
from these publically available sources.  State GIS data, where it exists, could be better
or worse, much worse in some cases.

[Boyd]

Excellent post. Yes, it is hard to get good data. I have found some pretty good data here in NJ - more than the other states I've looked at (NY, PA, DE, MD). In the end, unless you have personal knowledge of the area it will always be tough... there are some things that just can't be downloaded from the internet. 

I think desertfish11 needs to realize that the maps here are a labor of love on the part of their authors, and only as good as the available data. A word of thanks mixed in with the error reports would have been nice. 

I will not go into the history of the project as I observed it in Reston beginning
in 1982.

I would love to hear about that sometime myself.

[desertfish11]

I appreciate the background on that process of data entry. Sorry if I come off too bitchy with the reports guys, I'm just a dry scientist I guess 

On that note, while I'm getting to know the Santa Catalina mountains north of Tucson, or in other areas of Arizona, I'd love to contribute improved data on locations of named objects (and I don't mean my house and my favorite campsites), mostly just correcting the coordinates of the ones that were major enough to be recognized by the USGS. Is there a way I can help get better data onto the Arizona Topo map, or are these maps just not easily amended. I really have no clue cuz I'm a newb.