DisQuoi
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Posts posted by DisQuoi
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quote:
Can you explain how? ... I am unable to find where it does this.
Originally posted by Geo Leo:Mapblast will give you the coordinates if you enter an address.
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I had never thought of that. I just derived the coordinates of Moonshine Mountain by OUTSID4EVR & MAJELLIN by triangulating it from the three nearest caches. The error due to the rounding of distances to the nearest 100th of a mile was 131 feet. That's a pretty large search area.
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Your derivation of the intersection is the same I used in my spreadsheet that I provide finders when they need help with my YOU ARE THE GPS cache. Unlike your first solution, it only provided two intersections for two arcs. In that case, it's up to the finder to figure out which of 4 possible intersections is the correct one (the one common to all three combination of the three arcs). That way, they still need to understand the relationship between the locations of the satellites and the distances I provide in them. I'll definately hold on to your three-arc solution for my own future use, though.
(It might be worth pointing out that when using Warm Fuzzies' solutions, x**2 would mean x^2 or x-squared)
By the way ... some are saying that this is a way to locate members only caches. I tried this to locate Moonshine Mountain by OUTSID4EVR & MAJELLIN in Virginia and the error was 131 feet.
[This message was edited by DisQuoi on May 14, 2002 at 10:54 AM.]
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Here is a product that you can buy ... this links you to a demo page where you can try it out.
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quote:
That's pretty cool. I'd actually like to see the derivation. Is there code available that will compute two intersections of two arcs?
Originally posted by Warm Fuzzies - Fuzzy: Here's some Perl code that will calculate the coordinates of an unknown point if you give it the coordinates of three points and the distances from those points. -
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Originally posted by Markwell:First - DisQuoi: did you hurt your mouse finger when we bumped like that in posting?
No, I wear a protective foam helmut on my mouse finger for safety reasons.
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Originally posted by Markwell:First - DisQuoi: did you hurt your mouse finger when we bumped like that in posting?
No, I wear a protective foam helmut on my mouse finger for safety reasons.
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I have two caches here and here that requires the finder to triangulate (one mathematically and one with a map). I provide a spreadsheet to those who are unable to do it. The simplest way is to assume that the three reference coordinates are on a flat plane (close enough that the curvature of the earth is negligible) and convert to UTM. From here it's just an exercise in geometry/trigonometry.
I had started a similar thread on the subject and there were many good sources of help on doing this.
Keep this in mind ... the distances provided by the cache pages is only to 0.01 miles ... about 50 feet. Using UTM coordinates and the Pythagorean theorem, you can get exact distances. Of course you'de have to view the coordinates of the cache you're interterested in triangulating.
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Originally posted by mandingo:It would have made crossing the Atlantic Ocean a lot less boring
Actually, it would have been just as boring since there were no satellites sending you signals. I guess you could still play with the moon phase function.
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Originally posted by mandingo:It would have made crossing the Atlantic Ocean a lot less boring
Actually, it would have been just as boring since there were no satellites sending you signals. I guess you could still play with the moon phase function.
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Why would someone need permission from Jeremy to do this? ... It was a fund raiser for a library! There's nothing commercial about it. Someone donated a $50 gift certificate and people that wanted to play bought tickets. Now it's available to anyone who wants to find it. Who would [possibly] fork over money too them? ... maybe anyone who values literacy in their community.
Originally posted by The GeoGadgets Team:Non-profit, yes. But isn't this under the heading of commercial cache? Did these folks get permission from Jeremy, et al. before going ahead with this? And the most important of all questions: Who has found it so far?
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It's the old story of John Henry. In his case he used a hammer and a little piece of steel against a steam shovel and now some people are using map and compass against GPS. I don't think anyone's purposefully trying to exclude people that want to navigate using traditional means. The reason this activity has become so popular is that it allows anyone with a hundred bucks to do what otherwise only skilled map readers could do (I, being the kind with a hundred bucks).
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There's a good discussion of this at the this linked web page. After reading it (and the post of jfitzpat), I would say that the seasons are tied only to the tilt of the earth's axis. However, the temperatures on the planet as a whole may vary slightly depending on the distance from the sun but that's not the same thing as "Seasons". That is to say, while winters in the northern hemishpere might me colder due to the aphelion occuring in January, it's also resulting in cooler summers in the southern hemisphere.
Summer/Winter has nothing to do with distance from the sun, it has to do with the angle at which the sun hits the earth. Earth's axis being tilted and all. And that change IS big. -
I recommend the eTrex Legend. Mine was new for $220 including S/H. It's more or less the same as the Venture but included 8MB of memory instead of 1MB which alows for downloading of MapSource maps (at additional cost). Any other map software will work on your laptop but will not transfer to your Venture.
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"Here's your sign"
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"And yes, the above is rude, but does 'Due onto others...' ring a bell?" - jfitzpat to troll
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Everyone in this forum contributes to erosion and global warming. Every time you turn on a lightbulb, or put on a shirt that was manufactured, paddle your fiberglass kayak, tie on your rubber-soled-water-consuming-cow-skin-covered-Vasque-boots, or charge your electric scooter, you are contributing to the pollution and impact to this great Earth on which we live. I live in the East, but would love to preserve the desert and rocky regions of the USA so that my great grand children might see the beauty. Alas, many people like M. have chosen to live there, recreate there, and impact there. For a hiker (of all people) to ask me what I'm doing to assure that I don't trample the cryptobiotic soils really burns me. Move to New York City and live in an apartment building and stop kicking up the dust in Utah, will you?
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This Thread may answer your question.
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Originally posted by travisl:Trigonometry will tell me how far south and how far east to go, but still won't give me the final coordinates.
The beauty of UTM is that 1 unit = 1 meter whether you're looking at northing or easting.
Therfore, if you're at N122° 0.000' W47° 0.000' you're also at 576025 5205649. If you go 114 meters south and 114 meters east (0.10 miles or 160 meters x .7071), you're now at 576139 5205535 which is equal to N46° 59.937 W121° 59.911. (I rounded).
While I still relied on my GPS to convert UTM to/from Lat/Lon, I was able to calculate the same coordinate that you did using trigonometry.
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Don't worry about that. Now that you have learned that mathematicians and physicists have a frame of reference that is different from yours, you won't get as confused next time. Just remember ... always draw a picture and say out loud, "SOH CAH TOA" ... you should be okay.
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Actually, I wasn't aware that it was a game show. But since there is money on the line here, I'd better at least clarify my answer, Alex. My answer relies on the assumption of using the more widely accepeted CCW convention in which due east is zero degrees, due north is 90 degrees, and so on (counter-clockwise).
Bzzzzzt..... wrong answer, thank you for playing.Actually, it is the other way around...
sin(az)*D = dx, cos(az)*D = dy
Since the Oxford English Dictionary defines BEARING as The direction in which any point lies from a point of reference, esp. as measured in degrees from one of the quarters of the compass; also, the direction of an arriving radio wave or radar echo determined by a direction-finding system, I'm guessing that my original reply is valid.
In fact, both sets of formulae are correct as long as you understand what your frame of reference is ... but if you only know the equations and not the concept, I'd suggest you not use them for the very reason illustrated in this misunderstanding ... you might end up walking off of a cliff.
[This message was edited by DisQuoi on May 03, 2002 at 11:54 AM.]
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Actually, I wasn't aware that it was a game show. But since there is money on the line here, I'd better at least clarify my answer, Alex. My answer relies on the assumption of using the more widely accepeted CCW convention in which due east is zero degrees, due north is 90 degrees, and so on (counter-clockwise).
Bzzzzzt..... wrong answer, thank you for playing.Actually, it is the other way around...
sin(az)*D = dx, cos(az)*D = dy
Since the Oxford English Dictionary defines BEARING as The direction in which any point lies from a point of reference, esp. as measured in degrees from one of the quarters of the compass; also, the direction of an arriving radio wave or radar echo determined by a direction-finding system, I'm guessing that my original reply is valid.
In fact, both sets of formulae are correct as long as you understand what your frame of reference is ... but if you only know the equations and not the concept, I'd suggest you not use them for the very reason illustrated in this misunderstanding ... you might end up walking off of a cliff.
[This message was edited by DisQuoi on May 03, 2002 at 11:54 AM.]
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It's also very easy to do manually using trigonometry. The sin of the bearing times the distance will provide you the change in northing and the cosin of the bearing times the distance will give you the change in easting. This holds true if you're using UTM coordinates and the distance is small enough to consider that the curvature of the earth is negligible.
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After reading these ideas, I'm thinking of doing something like this ...
1) Mark 100 feet in a field and have each scout pace the distance a couple of times to determine their stride.
2) Give them instruction to complete a preset path of 4 or 5 legs.
3) Let each one carry a GPS strapped to their head (no looking) and let them attempt the route using only a compass and their newly found stride length.
4) Plot each scout's path on an aerial view so they can see how they did (against the preset path and each other)
This way, they will actuall learn something (their stride and the limitations of it) and they'll see a little bit of the technology as well. Maybe even let them try walking the route with the GPS (probably not since time won't allow for this).
The results can look somehting like this:
Any comments on this will be appreciated.
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One of our local Boy Scout Troops is camping this weekend and I've been asked to plan a 1-2 hours GPS activity for them in the morning. Besides finding the nearest geocache, does anyone have any good ideas for introducing them to GPS? (These boys are 12-14 years old)
How do you add Pictures to your Cache listing
in General geocaching topics
Posted
In fact, you can upload the image (<100kb) to your profile page then link THAT to your cache page. If you link to another website [even your own), the link could be broken in the future.