If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
396 question
Pretty kewl. Thanks for taking the time to explain.
"Travis Marlatte" wrote in message t... I work for NAVTEQ - although I am not directly involved in the data collection for our maps. The location of addresses is derived in a couple of different ways and it depends on the area as to how accurate it is. To save on space, the range of addresses for a block is usually all that is present. The location of a particular address, then, is merely an interpolation of where it is in the range. This usually results in the location being off by a small error. Less frequently, the addressing does not follow a logical pattern. The only solution is to identify the location of each and every address - which is only cost effective (both in data collection and in database size) in high volume markets. i.e. it's a balance of customer satisfaction and the cost of the database. Other possibilities are that we purchased data from a government entity and it is wrong. We do validate such data but it takes time. Validating is plain, old hitting the streets and comparing our data against reality. And, of course, it could just be a mistake. On the NAVTEQ website, there is a feedback section where you can report errors. Trust me, we review each and every report. NAVTEQ's website is www.NAVTEQ.com and the direct link to the feedback section is www.navteq.com/updates/mapfeedback.html. ------------------------------- Travis Lake N3094P PWK |
#12
|
|||
|
|||
396 question
Thanks alot for the background.
I haven't run into any significant errors so far (which is simply amazing). I love being able to use an address to find out where I need to go after I land. Travis Marlatte wrote: I work for NAVTEQ - although I am not directly involved in the data collection for our maps. |
#13
|
|||
|
|||
396 question, I have another quick question then!
Why does the 396 in "Automotive" mode sometimes take me off an interstate
off ramp, and then right back on the on ramp? Best, Karl ATP, CFI, ETC. World's most hangar queeny Skywagon http://temp.corvetteforum.net/c5/kgr...fterwaxjob.jpg "Travis Marlatte" wrote in message t... I work for NAVTEQ - although I am not directly involved in the data |
#14
|
|||
|
|||
396 question, I have another quick question then!
On 12/13/06 10:32, karl gruber wrote:
Why does the 396 in "Automotive" mode sometimes take me off an interstate off ramp, and then right back on the on ramp? Maybe it thought the car needed gas? ;-) |
#15
|
|||
|
|||
396 question, I have another quick question then!
"karl gruber" wrote in message ... Why does the 396 in "Automotive" mode sometimes take me off an interstate off ramp, and then right back on the on ramp? Best, Karl ATP, CFI, ETC. World's most hangar queeny Skywagon http://temp.corvetteforum.net/c5/kgr...fterwaxjob.jpg To avoid the Cop lurking under the overpass? gg Jay B |
#16
|
|||
|
|||
396 question, I have another quick question then!
karl gruber wrote:
Why does the 396 in "Automotive" mode sometimes take me off an interstate off ramp, and then right back on the on ramp? Perhaps because there was construction of some sort when the data was collected. I was amazed when I was on I-85 in Durham NC. The road was in the process of major overhauling - 2 lanes to 4, etc. It directed me off and along a section of service road that had not been put in service yet. The data reflected the way was going to be in a few weeks/months. |
#17
|
|||
|
|||
396 question, I have another quick question then!
"karl gruber" wrote in message
... Why does the 396 in "Automotive" mode sometimes take me off an interstate off ramp, and then right back on the on ramp? Best, Karl ATP, CFI, ETC. World's most hangar queeny Skywagon http://temp.corvetteforum.net/c5/kgr...fterwaxjob.jpg "Travis Marlatte" wrote in message t... I work for NAVTEQ - although I am not directly involved in the data I can share some of the issues that I am familiar with. Navigation systems are not running on the most powerful computing platform. So, anything that they do is a tradeoff between response time and quality. To find the truly optimal path between two points on the map is computationally prohibitive. The Route Calculation algorithm wants to find the least cost path from point A to point B. Lease cost may be defined as quickest based on predicted travel speed or smallest distance - combined with other possiblities like avoid tollways, avoid highways, etc. Every road in the database has attributes, a length and a speed. Even the intersections have tables to indicate the "cost" to get from one branch to another through that intersection. Techniques are used to reduce the amount of searching that must be done but these techniques sometimes result in far from optimal results. One of the popular algorithms that is used searches from both the origin and from the destination. During the search, branches are pruned off that don't seem to be going in the right direction. This, of course, sometimes eliminates one of the good routes. The other result is that sometimes the two searches meet but because of the ordering of the search paths, the first meet is not the best but somehow wins. Of course, the other problem is personal preference. My sound-bite is "only use a navigation system when you don't know where you are going and you will be please with the result. Use it to get to the office and home every day and you will soon conclude that it couldn't route itself out of a paper bag." It's going to be a long time before navigation systems will cut down that side street to avoid that typically long light. To address your specific question of ramp jumping, fundamentally, the algorithm believes that getting off and back on is shorter (or faster) than staying on the highway. I have seen several causes: 1) the user has chosen to avoid highways but there is no other way to get there. But, while determining the path, the algorithm mistakenly is still trying to avoid highways wherever it can; 2) for some reason, the cost of staying on the highway is less than using the ramp. This certainly could be a mistake in the data but it could also be a bug in the algorithm. 3) In pruning, the algorithm eliminated the path that stayed on the highway but then was forced to make a connection and the ramps were used instead. Another problem is that ramps are typically posted at something like 45mph. I know that, for a while, the algorithm we used presumed that people would drive them faster than coded which basically made them as good as a highway. Prune a few branches. Ignore some data. And, presto, the ramp is better than the highway. If you happen to remember the highway junction where that has occured, I can check our data. ------------------------------- Travis Lake N3094P PWK |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Lyc. O-360 cylinder question | JB | Owning | 13 | November 27th 04 09:32 PM |
Handheld battery question | RobsSanta | General Aviation | 8 | September 19th 04 03:07 PM |
A question on Airworthiness Inspection | Dave S | Home Built | 1 | August 10th 04 05:07 AM |
Question | Charles S | Home Built | 4 | April 5th 04 09:10 PM |
Partnership Question | Harry Gordon | Owning | 4 | August 16th 03 11:23 PM |