June 1, 2005
What's an orthophotomap, and how do I catalog it?
A cataloger asks this question on AUTOCAT:
I'm cataloging a map from our state Dept. of Transportation that has been released in 2 versions. Both are exactly the same map, except that one has been superimposed on top of an aerial photograph. Both have exactly the same title, size, scale etc. The only difference is that one says "Photograph not to scale" on the bottom and the other doesn't. (If the map is to scale and the photograph matches the map, then why isn't the photograph to scale too?)
Is there a standard terminology among map catalogers for a map superimposed on top of a photograph, and how in the world do I make the distinction between these 2 maps clear in the OPAC?
Here's the response from map cataloging guru Paige Andrew:
- The "Photograph not to scale" statement leads me to believe that the aerial photograph used as the base has not been "rectified", that is to say it has not been corrected for distances on the ground between known spots using an established national or international geodetic system. The only thing that is relavent about this for cataloging purposes is to possibly include this statement in a 500 note, because the scale statement IS given for the map, which should be used in the 255 field (and of course the 034 field). Why isn't the photograph to scale? Well, quite possibly it is a matter of nobody wanting or needing to make time to get it rectified before it was used for the purpose of a base map.
- Standard terminology for 300 SMD: Any remote-sensing image (the aerial photograph used as a base in this instance) that has map symbols and/or labels placed on top of it, such as latitude and longitude grid, placenames, spot elevations, road networks, river networks, etc. is considered a "map" and thus should be described in 300 $a as "1 map...." That said, if you were cataloging an aerial photograph or satellite image or other remote-sensed image just as it is, the 300 $a would read 1 remote-sensing image... Now, this doesn't necessarily help make each of these maps distinct in terms of the physical description -- you need to use a combination of notes, a specific subject
subdivision, and a specific subject code in the call number to make the "distinction" work, especially since the DOT failed to use a distinct title or alternate title to call out the difference between the two maps.
- Note(s), subdivision, subject code for the aerial-photo based map:
- This type of map is known as an orthophotomap and thus you can add a note that simply says "Orthophotomap" or be a little more descriptive and note that this map is an orthophotomap based on the other identical map.
- The specific subject subdivision to use in this case is "Remote-sensing map" as in:
651 0 $a Nevada $v Remote-sensing map.
- Using the LC G schedule, you will want to distinguish this map from the "plain" DOT state map by adding the subject code of A4 to the call number. So, to distinguish between the two maps, your call numbers would look like the following, and they will file either close to, or next to, each other in the map drawers:
"Plain" map: G4351.P2 2005 .N4
Orthophoto map: G4351.P2A4 2005 .N4
Questions? Contact Stacie.
Posted by trail001 at 10:43 AM
Trivia: What's up with 007 coding for CD speed?
A recent discussion on the AUTOCAT list addressed the reason why the speed of an audio compact disc is 1.4 meters per second (007/03 f). Just in case you're curious, here's a good explanation of why this is the case:
"CDs and DVDs address this by using what is called Constant Linear Velocity (CLV) The surface moves past the read head at a constant rate. This means as the pickup head moves from the center toward the edge of the disc, the disc does not have to turn as fast since there is more ground to cover. It is akin to the old "whirly go round" at the park. The kid on the outside had to run fast, but the kid in the center barely had to move. The rate chosen was 1.4 meters per second. As the disc plays, there is more "landscape" to record on so the disc doesn't need to move as fast."
Posted by trail001 at 10:30 AM