The "Coast to
Tiger Map Server
Frequently Aasked Questions (FAQ)
Is there any legal/copyright issues using these map?
No. The maps are public domain. You may use them how you wish.
How can I download the images I create?
That depends on your browser... With NetScape and Microsoft Internet Explorer you can Ctrl-Right Click *on* the image and you will get a menu with an option to "Save Image As...", or "Save Picure As...". Then you can just give it mapname.gif.
The map image is broken, What gives?
This could be a number of problems, but the most frequent is a browser problem... Some browser still dont recognize the HTML code
<INPUT; TYPE=IMAGE...>. I think Netcom NetCruiser still has this problem, and older versions of web browsers. You'll need to upgrade your web browser.
Why is this server sooo slow?
These machines generate 25,000 to 30,000 maps per day. The code is not terribly efficient and at times there are a *lot* of users hammering on the machines. All I can say is be patient.
Where are the street names?
We do not have funding and resources to improve/enhance the map server.
There are some programming problems with font rotation and scaling which
need to be solved. If you have any experience in this area, please send
me some email.
Sometime forcing on features doesnt work. What is the deal?
There are hardcoded thresholds for feature layers. Most of the features
wont display until you get to a map scale around 1:1500000. This threshold
was put in place to keep users from swamping the CPU with unreasonable requests. (eg. draw all streets at the US Level)
The legend on the Census Statistical Maps display garbage occasionally, What's up?
This is a known bug that we encountered when we moved the code to the SGI
machines. I am aware of it and will fix it, hopefully in the near future.
What happened to the resize map option? (ie. pixel height and width options)
It is still available from the URL http://tiger.census.gov/cgi-bin/mapbrowser. When we added the new border graphics around the map, I couldnt figure out how to resize them on the fly *and* preserving the integrity of the border image. When I tried it, it became distorted.
Which browser do you recommend to best view TMS maps?
I test with the latest versions of both Microsoft Internet Explorer and
NetScape Navigator. Everything looks and runs good with these packages.
If you are running an old browserr, try the old mapper at
URL http://tiger.census.gov/cgi-bin/mapbrowse. We wont be redesigning anything to accomodate
old browsers and we dont particularly want to hear about the problems with
them. Keeping your browser software current is *highly* recommended.
Why is this "geographic entity" not at the correct location?
The Census geographic product (Tiger, GICS, STF) definition for geographic
entities is based on an "Internal Point" which has a technical definition
An internal point is a set of geographic coordinates (latitude and
longitude) that is located within a specified geographic entity. A
single point is identified for each entity; for many entities, this
point represents the approximate geographic center of that entity. If
the shape of the entity caused this point to be located outside the
boundaries of the entity, it is relocated from the center so that it is
within the entity. If the internal point for a block falls in a water
area, it is relocated to a land area within the block. On
machine-readable products, internal points are shown to six decimal
places; the decimal point is implied.
All of the geographic location (lat/lon) values from the "New Location"
button and the US Gazetteer are derived from these calculated values. Alternate geographic values may
be obtained from the
USGS Geographic Names Information System (GNIS) database or by telnet
at the site martini.eecs.umich.edu at port 3000. Please remember the
TMS input is in decimal degrees and not Degrees:Minutes:Seconds.
How can I add marker(s) to the output image?
How can I get the LAT/LON of a specified point?
- Adding a Single Mark or Obtaining LAT/LON for a specified point:
For a single marker, you can choose "Place a Marker" on the radio
buttons to the right of the map, section that says "CLICK IMAGE TO:"
Now, look down below the map, under "Place Marker on Map" and select
the desired "Symbol". The click on the map itself. It should
redraw with the marker placed where you clicked. Once the map
redraws, scroll down to "Place Marker on Map" section and you
will see the LAT/LON of where the marker was placed.
(That is how you get the LAT/LON of a place you clicked)
- Adding Multiple Marks on the URL:
For an example of placing multiple markers on the URL, the syntax
is: mark=lon,lat,symbol,label;... an example:
Here is an inventory of available symbols. If you would a custom symbol, please email to Chris.Stuber@Census.GOV.
Multiple Marks may be placed on the URL only. There currently is not an interactive mechanism for placing multiple markers on the map, one at a time.
- Adding Multiple Marks from a remote file/URL (MURL):
For *many* marks, you will need to review the URL
Look at http://tiger.census.gov/instruct.html
and look at the &murl; option. Deriving marks from a remote
If you would like to ask a question or make a comment, please check out the
Mapsurfer Feedback page
Last Revised: Sunday, 27-Apr-97 23:40:31