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Frequently Asked Questions

This FAQ is very much in progress. You can help out by asking the questions you think should be in it. Frequently. Also, check out the Information pages for many answers. The FAQ is maintained by Gilles Kohl.

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Disclaimer and warning: Seeking and visiting confluences may entail risks and unknowns of various types. While confluence seekers may submit their results to the project, they are acting on their own behalf. The project will not be responsible for any damages or injuries caused or incurred. Seekers need to evaluate potential risks and damage, make informed judgments on their own, and only pursue activities where they accept all responsibility.

1. General information

2. Organizational questions

3. Visiting confluences

4. Equipment

5. Photographing confluences

6. Navigation

7. Confluence classification


General information

1.1 What is the Degree Confluence Project?

The goal of the project is to visit each of the latitude and longitude integer degree intersections in the world, and to take pictures at each location. The pictures, along with a narrative, are then posted on this web site. This creates an organized sampling of the world.

Another goal is to document the changes at these locations over time. Although we initially want to visit as many different locations as possible, don't hesitate to revisit a confluence if you're in the area.

1.2 How was the project started?

I (Alex Jarrett) started the project in February 1996 because I liked the idea of visiting a location represented by a round number such as 43°00'00"N 72°00'00"W. What would be there? Would other people have recognized this as a unique spot? Another reason was that my friend managed to convince me to buy a GPS and I had to come up with something to do with it. I also hoped to encourage people to get outside, tromp around in places they normally would never go, and take pictures of it.

I visited several confluences of my own and posted them to my personal web site. Before long others found the site and visited confluences of their own, and it just snowballed from there.

1.3 What is a confluence?

A confluence is defined as a flowing together; a meeting place (often of rivers).

In our case a degree confluence is the exact spot where an integer degree of latitude and an integer degree of longitude meet.

1.4 Why go confluence hunting ?

There probably are as many different answers to this question as there are confluence hunters, but here are a few reasons:

1.5 How many confluences are there?

There are 64,442 latitude and longitude degree intersections in the world (counting each pole as one intersection). After discounting many confluences near the poles, and in the oceans, 16,347 meet the goals of the project, with most of these (14,029) being on land. There are still 10,044 to be found, so as you may guess, we're not worried about running out of confluences.

1.6 How many confluences are there in my country / state ?

To find out how many confluences are in your country, find it in the country list page. If your country has states / provinces / departements etc., click on it, a list with the corresponding subdivision statistics will open.

1.7 What is a primary confluence? What about aerial and water confluences?

A confluence is primary if:

  1. It meets the criteria outlined in the Poles Problem section.
  2. It's on land, or if in a body of water or ice, within sight of land, so that, on a clear day, discernable land features can be recognized.

All other confluences are defined as secondary. They will be accepted if visited but are not part of the primary goals of the project. Note that ANY visited confluence, regardless of whether it is primary or secondary, will be added to the site, even if it is not currently indexed in our database.

Aerial photos are not considered successful visits though, and will be posted as incomplete visits. They are very useful for planning a ground-based visit, and add to a successful visit.

1.8 How can I help out?

If you would like to volunteer to help us with the management of the project, please use the contact page.

1.9 Do you have all successful confluences so-far on a CD-ROM?

No, we do not have a confluence CD-ROM currently - the site is way over a Gigabyte in size and wouldn't fit on a CD-ROM. Also, new visits are added daily - a CD-ROM would very quickly become outdated.

1.10 Where are you located?

There are several answers to this question.

Organizational questions

2.1 What about confluences on private land ?

If the confluence is located on private land, always ask permission of the landowner before trespassing, especially if the land is posted "No Trespassing." Take along a copy of the Letter to Landowners to help with this.

You should always first ask for permission before visiting the confluence if it is on private ground. Offending visits have been and will be removed from the site.

2.2 Is confluence hunting subject to legal restrictions ?

Confluence hunting per se is no problem in countries that have individual freedom of movement, as long of course as you don't trespass (see above) and stay away from military installations.

Note that some countries prohibit private use of GPS devices or require permission to use them. For instance, Russia and China require permission.

If you have doubts about a specific country (especially if going on vacation there), try to get information beforehand (e.g. from your travel agency, the Embassy or Consulate office of your destination country etc.)

2.3 Who pays for this ?

It's basically free. A few costs, such as the domain registration fee, site maintenance costs, etc., are covered by sales of T-shirts, mugs, caps, and also calendars.

Many volunteers help run the site.

2.4 What is confluence verification, how and why is it done ?

Verification is to weed out bogus submissions, and to check for obvious errors. Basically, we trust people, unless we can show that it's not at the right spot (usually by comparing with a map) or the narrative clashes with the pictures, then it will be more thoroughly verified.

Sometimes the coordinators need to correspond with the person who submitted the report (e.g. to clarify the narrative or picture captions), and in these cases, a report may stay on the pending list in an intermediate status (verified or ready) for a period of time before being made active.

2.5 How does a confluence report get removed from the pending list?

Confluence reports are processed by regional coordinators - (check the contact page for a list of current regions and their coordinators) - when a confluence report is submitted, the corresponding coordinator is notified by email. At regular intervals, coordinators process the reports, which consists of verification, processing pictures (e.g. resolution or format conversions) and reviewing narratives (typos, hyperlink insertion etc.). The final step is to set the report status to "active", which causes the report to show up on the site, automatically sends a notification email to the person who submitted the report, and automatically removes the confluence report's entry from the pending list.

2.6 What are Special Visits?

A visit, including narrative and photos, to a non-confluence location may be posted on this website as a Special Visit.

The determination of whether a non-confluence visit is Special is made by the regional coordinators. If you are considering a visit to a location you think may qualify as a Special Visit, it is best to contact your regional coordinator first, in order to see if your location will be considered as Special. Keep in mind that the goal of the project is documenting degree confluences.

Locations that qualify for Special Visit status include places that have a connection to the history of latitude and longitude, navigation, and mapping. There needs to be some sort of formal recognition of the location, such as a building, plaque, or monument.

Visits to "center of" locations are normally considered only if it is the center of a large area such as a continent or subcontinent. Visits to the center of a Country do not qualify as a Special Visit. Visits to 'boundary multipoints' do not qualify as a Special Visit.

If, as part of your travel to a degree confluence, you also visit a location that doesn't qualify as a Special Visit location, but which is an 'interesting location', you can include it as part of the narrative and photos for your degree confluence visit submission.

2.7 Are there any "confluence" events around the world ?

Not yet. Alex Jarrett revisited his first confluence with a few people (mostly friends). The Polish confluence hunters had a meeting (at the last remaining confluence in Poland), but that's about it for now.

2.8 The altitude value for a given DCP shown on the web site seems wrong ?

The approximate altitude shown for a given confluence is based on data imported from external sources, and may not be accurate. (It is usually an average value for an area of e.g. a square kilometer around the confluence - depending on the exact location of the confluence and the terrain, the actual value may differ slightly or largely.)

If you can document the correct altitude for a given DCP (taking into account the limits of GPS receivers), please let us know by contacting the corresponding regional coordinator.

2.9 How can I edit a published confluence to correct mistakes?

Once a visit is submitted, and the coordinator has made it active on the website, you cannot make changes to the visit, even to correct mistakes. If your visit is active, and you notice a mistake, contact the regional coordinator who processed your visit, and they will make the correction(s) for you.

Please carefully check your visit submission, by using the "Preview" link on your Member page, BEFORE finalizing your visit submission.

Visiting confluences

3.1 How do I find a confluence?

We have a Confluence Hunting Checklist that should cover everything you need to know. If you need more information, contact us.

3.2 How close do I need to be?

The accuracy of the confluence must be to within 100 meters. The accuracy of a standard civilian GPS is around 35 meters in the worst of conditions. If you're using a GPS, check if it has an averaging mode, which, if you can afford to sit still for awhile, will cause the GPS to settle down to a point where it knows its position more accurately.

The official datum of the project is the WGS84 datum. This is the standard for GPS devices. If you're using an older USGS map that uses a different datum, such as NAD27, you may need to convert between them. A web site with more information on this subject is http://www.colorado.edu/geography/gcraft/notes/datum/datum_f.html.

3.3 Which confluences are left to find - is there a list ?

There is currently no global list of unvisited or incomplete confluences, but you can figure out which ones are still available by checking the country page of the country or state (and neighbouring ones) you would like to visit.

If your country of interest is not listed on the left side of the confluence.org homepage (because it does not have any visited or incomplete confluences), try the "All countries" link. Once you have found the country, see if there are any available confluences for e.g. Austria, the "(12 of 12)" behind the country name indicates that all confluences in this country have been visited.

For countries with subdivisions (e.g. states in the US, départements in France, Bundesländer in Germany ...), repeat the procedure above.

For a more visual check of what confluences have been visited and which ones are still available, check out the links under "Worldwide Maps". Finally, don't despair if all confluences in your area have been visited - a second visit e.g. during another season can add value by showing how the spot changes over time. Other creative alternatives could be visiting with more people, improving on the narrative, having a meeting with several fellow confluencers etc.

3.4 Should I leave some sign or marker at the confluence ?

The goal of the project is to visit confluences and take pictures, which does not require the confluence position to be 'marked', either temporarily or permanently.

Some confluence visitors use some form of 'marker' while taking pictures at the confluence. These 'markers' include things such as a flag or sign or plaque, a personal item such as a hat or backpack, or local items such as sticks or rocks.

Many confluence hunters stick to the Golden Rule for camping and hiking: "Take nothing but pictures, leave nothing but footprints".

(Confluence seekers are acting on their own behalf, and it is therefore their decision as to whether it is appropriate to leave a 'marker' at the confluence. The policy of the project is that if a 'marker' is left at a confluence, it should only be done with the landowner's permission, or, in the case of public lands, in accordance with any governing policies or legislation. We would like to strongly discourage the leaving of a permanent marker especially in wild areas though.)

Also note that confluence pictures with signs or markers do not meet the photo requirements.

3.5 Is there any value in visiting a confluence already recorded by another?

Yes, definitely. We accept all visits to confluences, and we welcome revisits. One of the goals of the project is to document the changes to a spot over time. Please submit any visit you have made!

Don't be discouraged that you would "only" come second - no two confluence visits (for the same spot) are the same, and your narrative may provide valuable information (and interesting reading) for future visitors and DCP enthusiasts. While there are still many unvisited spots to photograph, in some regions nearly all spots are visited and people start revisiting, with interesting results. Some note that their GPS leads them to a slightly different spot than their predecessors, with others the pictures are entirely different since they visited in another season, and still others have interesting encounters with the locals.

Sometimes, the evolution over time is documented, for example the consecutive visits to this spot (50°N 6°E) trace the erection of a marker at the confluence.

3.6 I'd like to check for confluences in a given country, but can't find it on the country list ?

The list on the homepage has only countries with at least one successful or incomplete visit. (The figure in parentheses is the number of successful visits).

The country you're looking for may not yet have any posted visits at all, in which case it is listed on the "All countries" page only.

3.7 Do plans to visit a confluence need to be arranged in advance, or can photos from a trip previously taken suffice?

Submissions from trips specifically done to visit a confluence are preferred of course, but if you are really sure your visit meets the requirements, please submit it. As you probably won't have a GPS picture or even have planned using detailed maps, providing sufficient proof that you were within 100 meters of the confluence will probably be the most difficult part. The pictures you provide will also have to meet the photo requirements.

3.8 Can I reserve a confluence to visit e.g. next month?

You can tell fellow confluence hunters that you intend to visit a given confluence point via the "plans" device. To do this, log in to your account via the member page (you can also create an account here if you did not do so already), and click "View your Plans", then fill out the form as instructed. The confluence page will then list your plan.

Note that this is not a reservation in the way you would make a reservation for a restaurant table - if another visitor submits first, (s)he'll still be listed first on the site.

Equipment

4.1 What is the equipment recommended ?

The minimum equipment is a good map, a camera, and a compass. For details, check out the Confluence Hunting Checklist.

The first step is finding a good map of the area. If you don't have a GPS, the map must be an extremely detailed, e.g. 1:25,000 or better scale topo map, or a use map program, or a map from a good internet mapping site (see the links page for a list of those).

If you have a GPS, you'll still need a decent map to get you in the general vicinity, and then you can zero in on the confluence with the GPS.

The recommended equipment is (again) a good map of the area, a GPS receiver, a digital camera (resolution of at least 600x400x16), and a compass. If you're going alone and want to take pictures of yourself at the confluence point, a tripod for your camera is a good idea - also useful for panorama shots. A ziploc baggie sometimes comes in handy if it rains and your GPS device isn't waterproof.

4.2 Can I submit a confluence without using a GPS receiver, but a good map instead ?

The GPS receiver is not required, although it helps a lot to pinpoint the exact location. If you do not have a GPS and cannot borrow one, make sure you have a very detailed map of the area, a good compass, and good navigation skills. Satellite photos available from terraserver may help locate the right spot in this case. Remember - the rules of the project require you to be within 100m of the confluence point.

4.3 What's the cost of a GPS instrument?

Your mileage will vary of course. There are several types of GPS devices - e.g. those best suited for recreational use (hiking, boating), car navigation, marine use, surveying, the military ... prices vary accordingly, from around $100 to above $10,000. Check the Amazon link below to get a list of prices for consumer-level GPS.

The good news is that for confluence hunting, a relatively inexpensive (couple 100 US$ or Euro) handheld hiking GPS is well-suited. Getting a representative sample of what devices confluence hunters currently use is simple - check out the visit reports and look at the GPS device pictures usually found there.

Mapping capability is nice to have, but not a must - most probably, the maps will NOT show the immediate vicinity of the confluence spot since they are not detailed enough yet.
The device should ideally be waterproof, rugged, small and portable, with a good battery life. A PC cable is nice to transfer waypoints, routes, tracks etc. - check out these sites for more information:

Our links page also has a GPS section with additional GPS-related links.

Photographing confluences

5.1 What size / resolution should the photos be that I upload ?

The minimum size is 600x400 pixels with a color depth of at least 16 (65536 colors) We'd love to have images that are as detailed as possible, up to the 4MB per image upload limit. 1600 by 1200 can work. Then we reduce them for the web, but save the originals for the archives. So don't be afraid to upload high resolution pictures. The preferred format is JPG.

5.2 What should I take pictures of, and how many of them ?

The following is a summary, see the photo requirements for details.

We want five or six pictures total: 2 to 5 from the confluence spot or of the confluence spot with no people in the pictures (unless they live there), and, optionally, 1 to 4 with the confluence visitors, or of the journey to the confluence.

Note that visits that do not contain at least two photographs of the general area within 100 meters of the confluence will be posted as incomplete visits.

You may take pictures of the four compass directions, or put together a panoramic shot, or just show the most interesting features of the area. Try to give in your pictures the same impression you got when you were there. It is optional to take a picture of the GPS reading the confluence location. Please read the Copyrights/Permissions section on the 'Information about the Degree Confluence Project' page.

5.3 How do I make those 180 and 360 degree panorama's?

You will need additional software to do this. The basic principle (at least with a conventional digital camera) is to take several overlapping shots sweeping the horizon. Some cameras have a special mode to assist panorama shooting (called e.g. stitch assist mode), but additional PC software is usually required to assemble the individual photos into a single panorama picture later at home. A tripod is very helpful to assure your pictures are level and not askew.

Check out the panoguide website for further information on this topic.

Navigation

6.1 What is latitude & longitude ?

Explaining this in detail is beyond the scope of this FAQ, but if you missed Geography 101, check out this NASA page for a good explanation.

6.2 Where is 0 degrees latitude & 0 degrees longitude?

Every point located on the equator (an imaginary great circle passing round the middle of the Earth) is at zero degrees of latitude.

Zero degrees longitude is every point on the Greenwich Meridian or primary meridian - an imaginary line which runs from the North Pole to the South Pole. By international convention it runs through "the primary transit" instrument (main telescope) at the Royal Observatory in Greenwich. Check out the Royal Greenwich Observatory special visit. The point where the equator meets the prime meridian is situated in the atlantic ocean unfortunately (about 600km south of the town of Accra in Ghana), so it is not a valid degree confluence point for the project. (There would only be water on the pictures)

6.3 How do I find the latitude and longitude of a city?

Check out the "Mapping and Geography" section on the links page - especially the MapBlast and MapQuest links.

6.4 What is the northernmost latitude of the lower 48 states of the US ?

(Question submitted online, answered by our resident Dr. Geo, who's got a confluence degree :-)

Interesting question although not totally relevant to project.

The northernmost latitude of the lower 48 states is NOT 49N as one might expect at first. It is the Angle Inlet at about 49°23'N in Minnesota.

Here's more on this piece of trivia.

6.5 How many total intersections are there on land?

There are about 14,000 confluence points on land. For more details, please see the answer to How many confluences are there ?

6.6 What is the Highest/Lowest confluence?

The highest confluence - at about 6000 meters above sea level is 28N88E in China

The lowest confluence, at about 60 meters below sea level is 30N27E in Egypt

6.7 How do you convert degrees, minutes, and seconds to and from a decimal number?

6.8 What is the distance from one confluence point to the next ?

Well, it depends a little. If you want to reach the next confluence point to the north or to the south, the distance is always the same, or it would be if the Earth were a perfect sphere: it varies only from 110.57km (68.71mi) at the equator to 111.69km (69.40mi) between 89 degrees latitude and the poles.

If you want to reach the next confluence point to the east or west, the distance depends on how far north or south you are. The distance is 111.32km (69.17 miles) at the equator, and decreases with increasing latitude.

In other words, the closer to the poles you are, the nearer the next confluence point to the east/west becomes. At 89 degrees latitude, you can encounter a confluence point every 1.95km (1.21 miles) going east or west. (This is the reason for the Poles Problem)

To compute the distance in east/west direction, given latitude, the following formula can be used:

   Distance in kilometers: 111.32 * cos(Latitude)
        Distance in miles:  69.17 * cos(Latitude)

   (Calculator should be set to degrees, if radians use cos(Latitude/180*3.14159265))

Confluence classification

7.1 Why is a visit listed as incomplete?

An unsuccessful visit - i.e. one that did not get within 100m of the confluence point - is an incomplete visit. We encourage visitors to post those visits if photos and a narrative are available, as a way to document your effort and also to provide potentially valuable information for those trying the next visit.

Visits which do not meet our Photo Requirements and/or Narrative Requirements will also be listed as incomplete, even if the visitor got to within 100 meters of the confluence.

7.2 What's the difference between a "primary" and a "secondary" confluence ?

A primary confluence is one that meets the primary goals of the project, that is, it is on (or close to) land, and not ruled out by the "Poles Problem" restrictions. Check out "What is a primary confluence" above for more details on this.

A confluence that is on (or close to) land, but ruled out by the Poles rule is called secondary. Confluence points of this type will be accepted if visited but are not part of the primary goals of the project.

7.3 For some confluences, the latest succesful visit isn't the one that is featured, why ?

As an example, take a look at 54N 123W:

There are 3 successful visits:
#1: 11-May-2002
#2: 10-May-2002
#3: 12-Aug-2003

First, the reason that the "first" visit(#1) has a later date than the "second" visit is that the visit number is determined by the order visits are submitted to our site. The visit number is not used to determine the 'most recent' visit, or for anything other than to distinguish one visit from another.

You'll notice when you visit the above page that by default you see visit #1 listed, rather than the most recent successful visit, #3. That is because unless a specific visit is requested, we show the "most successful, most accurate, most recent" first.

To determine this for yourself, you have to know that the "Accuracy" field, shown on the left-hand side of the page, is not displayed when the value is 0, or 100.

In this case, all three visits are sucessful, so it's a 3-way tie. However, the next criteria, accuracy, puts #1 in the lead, because of it's value of 5 meters, compared to #2 at 8m, and #3 at 10m.

Had visits #1 and #2 both had the same accuracy value, then #2 would have been the one displayed, because of the earlier visit date. Regardless of visit date or accuracy value, a successful visit will be shown in preference to an incomplete visit.