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Old 18-07-2006, 14:31   #1
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Scanned Charts on the computer...

Are there any navigation programs other than the free-ware SeaClear (www.seaclear.net) that allow you to use self-scanned papercharts in electronic navigation?

I am (slowly) being dragged into the 21st century by the benefits of computer aided navigation, but INSIST on paper charts on board. Right now there seem to be three ways of doing it:

* Buying a full set of paper charts AND a full set of electronic charts. Very Expensive!

* Buying a full set of electronic charts and printing them all out. Time consuming and still not cheap, and without a big and expensive printer, you end up with marginal paper copies.

* Buying a full set of paper charts and scanning them in to the computer. Time consuming and cheap(er).

I have had good success "scanning" charts with my high-end digital camera. Am I missing something an alternative?
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Old 18-07-2006, 14:47   #2
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""* Buying a full set of paper charts AND a full set of electronic charts. Very Expensive!"
Sure, but the NOAA electronic charts that used to cost a fortune from Maptech, are online FREE now. From both NOAA and Maptech. So they're no longer expensive, they're free.

"* Buying a full set of electronic charts and printing them all out. Time consuming and still not cheap, and without a big and expensive printer, you end up with marginal paper copies."
If you only print what you need, you can spread the expense. Still, you'd need an 11x17 inch printer at the minimum and what you print won't be as water-resistant as the real thing. But depending on where you sail, chart books or used chart books might be enough for the "backup" version, with a printout of the electronic one when or as needed.

"* Buying a full set of paper charts and scanning them in to the computer. Time consuming and cheap(er)." If you're outside the US and need more than the NOAA charts, sure. Pain in the but if you cross over into Canada up by Vancouver and need all their charts too.<G>

"I have had good success "scanning" charts with my high-end digital camera. Am I missing something an alternative?" Bad idea. You are almost guaranteed to get keystone distortions, which a scanner wouldn't have.

Used, new, free...all depends on what you need and where and why you need it. For some trips, a AAA map really *is* good enough. Not many...but some.<G> And sometimes they show the YC's by name, which the marine charts don't.
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Old 18-07-2006, 15:09   #3
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Originally Posted by hellosailor
""* Buying a full set of paper charts AND a full set of electronic charts. Very Expensive!"
Sure, but the NOAA electronic charts that used to cost a fortune from Maptech, are online FREE now. From both NOAA and Maptech. So they're no longer expensive, they're free.
Did I mention that our cruise is mostly outside of the US? Guess not! I have already downloaded the full set of US charts. (Thank heavens for high speed connections!)

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Originally Posted by hellosailor
"* Buying a full set of paper charts and scanning them in to the computer. Time consuming and cheap(er)."
If you're outside the US and need more than the NOAA charts, sure. Pain in the but if you cross over into Canada up by Vancouver and need all their charts too.<G>
Actually, we were planning on going south, but your comment applies to Mexico as well...

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Originally Posted by hellosailor
""* "I have had good success "scanning" charts with my high-end digital camera. Am I missing something an alternative?"
Bad idea. You are almost guaranteed to get keystone distortions, which a scanner wouldn't have.
Ah, but you can easily correct such distortions with Photoshop :-) I import them after all the lat/long lines are straight and parallel. Done with care, it really does work. Being full time liveaboards, we don't really want to devote the space to a large format printer OR scanner!
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Old 18-07-2006, 15:33   #4
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Ah, outside the US charts are usually government property and cherished as valuable crown property. None of this "we the people" communism.<G>

Used charts and photocopies, are what I keep hearing. A large format printer isn't all that much larger, by the way. It just needs to get 2-1/2" wider in order to print 11x17 instead of 8-1/2x11, the other dimensions don't have to change. The scanner...can't help you there.<G> You can buy a slim one and scan and stitch, but unless you've got a very expensive high-dpi camera, you won't match the quality of scans. A scanned chart piece, 11x17 at 150 dpi (about the least acceptable resolution for this) is 4.2 megapixels. And you'll be losing some detail at that point. I guess that's just enough for what you need, if you don't have JPEG losses.
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Old 18-07-2006, 15:46   #5
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Try Fugawi

Try Fugawi Marine ENC . It'll take both vector and raster charts and you can also scan you own and import and calibrate them. It's a Canadian product, not too pricey as far as these things go(about $200) and comes with all the free charts (all NOAA RNC and ENC charts) in a DVD. And you also get a US or Canadian Street Map that can be overlaid on the chart.
http://www.fugawi.com/
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Old 18-07-2006, 15:52   #6
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I have heard that the AIS implementation on Fugawi was, well, marginal. Any experience that you could add about that?
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Old 18-07-2006, 19:43   #7
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I don't use the AIS under Fuagwi but they have the best ENC display going save for a commercial product I saw for commercial ships. Most of the other packages really are quite poor at ENC. Scanning is pretty simple you scan the chart then input the Lat / Long coordinates for the corners. The trick is of course scanning a a large area at one time, but you can have it cheap or easy.

It does BSB well too but for ENC it is really great. You just load all the charts and it knows what to use and they all display seamlessly. Scale is not an issue.

Around here AIS isn't much use. The US Navy is pretty frank about when they are around and they throw you in jail before they hit you. The commercial boats are boxed into a narrow channel and are moving too fast to stop, slow down or hail you, but you know where they will be.

The last release added AIS and they maybe could do a better job of it. You still need a second serial port to use it. But they do add weather FAX overlay if you want it. You need to spend double to get more than you get with this product and in some ways you don't get that much more.

Pricey? At $200 Fugawi is half the major players price. For the high end RayMarine product you are talking a whole lot more than double. Persoanlly, I don't think the the Sea Clear product is worth free. You need to spend some money for charts at some point unless you remain in US waters all the time so in the overall scheme the price of software is peanuts. I also know of no single product that does the whole world well so you may need at least two software products to cover a world cruise electronically.

Just for the record you can't correct maps in PhotoShop, but you can think you can. A scanned map is a one off and less accurate. There are things you can't fix. It's does not mean it won't work. Magellan sailed with some pretty worthless maps. It's all how you deal with it. Information is always inaccurate in some way. You just learn to deal with it.
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Old 18-07-2006, 20:53   #8
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IJust for the record you can't correct maps in PhotoShop, but you can think you can. A scanned map is a one off and less accurate. There are things you can't fix. It's does not mean it won't work. Magellan sailed with some pretty worthless maps. It's all how you deal with it. Information is always inaccurate in some way. You just learn to deal with it.
Curious! Why is it people keep saying what I do can't be done?

Here's the procedure:

I use a Nikon D50 with an 18-50 f2.8 Sigma lens. Charts are taped flat to the floor, and the camera is mounted on a tripod, carefullyadjusted to ba as parallel to the floor as possible. Settings are identical each time so I don't need to experiment. The file is saved and manipulated as a raw file, so all of the detail is retained as long as possible.

Any deviation from non-parallel is easily corrected in Photoshop with the perspective crop tool and using ruled paper I know exactly the amount of barrel distortion to remove with the lens correction filter.

SeaClear comes with a import tool that allows me to put reference points on the in as many places as I need (minimum of three).

I have done this with local charts that I have official scanned copies of, and the resolution is obviously not quite as crisp, but it is totally readable, and I have not found the homemade version to be off register in longitude and latitude far enough to measure. I can do a section of paper chart up to about 16x20 in one go.

So why can't I correct the maps in Photoshop? Or are we talking with different definitions of what we mean when we say "correct"?
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Old 19-07-2006, 07:04   #9
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Not that it can't be done (at least not by me) but that with even the best technique, the equipment you have is marginal for the job. Capable, yes, but still marginal. The D50 is a 3.3megapixel pixel, your best print placed side by side with a printed chart would be the obvious copy, not as clear and sharp. In your case you're down to about 110dpi for a 20" wide chart, which I'd call soft and fuzzy if you print 'em that size. But I've also nagivated with small fuzzy photocopies that must be worse than what you're making--and hey, at the time, they were all I needed and wanted to pay for. I can appreciate that!<G>
But that's also equally obvious with the old fashioned chart books--which were made the same way using a graphics copy camera. You're doubly-disadvantaged against that because the D50 lens is not a "flat field" copy lens, like all consumer optics it is designed for greater depth of field and sharpness in a 3D zone, not a flat field. (Nikon made/makes some great flat-field lenses for their SLRs. Again, you'd have to put the work from them side by side to see the difference, but they pop.)
And the copy charts also suffered keystoning. I wouldn't be surprised if Photoslop (software we love to hate<G>) could correct that by now, again given a careful user. Still, it leaves you open to distortion and a longer process.
But as Galileo supposedly said "Nevertheless it turns!" if it works for you, that's all that counts.

(Gotta update my old Photoslop, there was no perspective correction tool in it. Adobe was always behind the competition in their feature sets.)
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Old 19-07-2006, 09:25   #10
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Not that it can't be done (at least not by me) but that with even the best technique, the equipment you have is marginal for the job. Capable, yes, but still marginal. The D50 is a 3.3megapixel pixel, your best print placed side by side with a printed chart would be the obvious copy, not as clear and sharp. In your case you're down to about 110dpi for a 20" wide chart, which I'd call soft and fuzzy if you print 'em that size. But I've also nagivated with small fuzzy photocopies that must be worse than what you're making--and hey, at the time, they were all I needed and wanted to pay for. I can appreciate that!<G>


The D50 is a 6.1 megapixel camera and a 16x20 copy area is done at 150DPI, granted not the same as a offset press, but pretty good, and you're right, a lot better than those fuzzy old photocopies that all cruisers have used at one point or another.

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You're doubly-disadvantaged against that because the D50 lens is not a "flat field" copy lens, like all consumer optics it is designed for greater depth of field and sharpness in a 3D zone, not a flat field. (Nikon made/makes some great flat-field lenses for their SLRs. Again, you'd have to put the work from them side by side to see the difference, but they pop.)


Obviously you are confused... the D50 IS an SLR... and the Sigma lens I am using is certainly not "consumer optic" grade glass. Granted, it is not a purpose built copy lens, but it has excellent focus field flatness and corner sharpness, when used at middle of the zoom and aperture ranges. Certainly it would have difficulty with generating a good copy of a PHOTO, but we are dealing with very simple, unsubtle images here, that are very easy to post process to excellent sharpness. This is not a technique for someone un-skilled in photography or digital photo manipulation, but it works, and works well when done with care.

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And the copy charts also suffered keystoning. I wouldn't be surprised if Photoslop (software we love to hate<G>) could correct that by now, again given a careful user. Still, it leaves you open to distortion and a longer process. But as Galileo supposedly said "Nevertheless it turns!" if it works for you, that's all that counts.


Photoshop has had very functional perspective cropping for many versions. The CS2 version of this tool is even better.

What I described is not a theoretical process, it is what I DO successfully. I really do not understand why people are so ready to tell me what I know DOES work can not be done, but have no useful suggestions for my original question... Ah, the Internet!
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Old 19-07-2006, 09:40   #11
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Never having laid hands on the D50 I only looked it up online, where I saw it spec'd at 2256x1496 pixels, which multiplies out to 3.3mp. I found another review claiming it is more like 3000x2000 at maximum...sounds like Nikon changed the image sensor somewhere between pre- and production. 6mp is nice!

"I really do not understand why people are so ready to tell me what I know DOES work can not be done, but have no useful suggestions for my original question..." I think you only got one vote for "not work", versus a couple of suggestions for obtaining charts. Which AFAIK include all the limited options there are, besides "Take the Queen hostage and don't return her until she agrees to give the order to release charts to you."

I'm afraid that could be like "The Ransom of Red Chief" otherwise I'd have mentioned it sooner.<G>
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Old 19-07-2006, 14:50   #12
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I am happy with my electronic charts, but also maintain a passage paper chart, and use pilot books for the detailed stuff to confirm what I am seeing - my electronic chart has good harbour plans anyway, and I maintain it against a calibrated satellite image which by "tab/alt" I can cross compare.

works for me!
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Old 19-07-2006, 15:16   #13
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I maintain it against a calibrated satellite image which by "tab/alt" I can cross compare.
You need to be extra careful with these. They do not have that great an accuracy. Before you even get them they have radial distortion that you can't calibrate using any over the counter process. In general it can't be corrected. Using as is is perhaps just as good. Once you attempt to calibrate it, the distortion generally gets worse but "looks" better.

Confirmation from multiple sources clearly is the critical part of navigation many people miss. No information is really perfect. It's nice to have several things telling you what you want to confirm.

I would just be careful when the imagery disagrees. It could send you places you don't want to go. It's one of those errors where you are dead sure you are right and actually dead wrong you end up doubting the good stuff. It basically comes down to when it agrees it is fine but when it does not don't believe it. I just would never doubt a chart over it.
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Old 19-07-2006, 21:26   #14
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The lawers would have a field day...

GreatKetch,
I have a Pentax with the exact same lens that you describe on my desk and I have played with Seaclear.
Yes, I think that you could get useable copies in the way that you have described.
To me the problem that you are looking at is that the marine community is very conservative and has a huge investment in existing maps/equipment.
There is almost no experience in working the way that you are describing.
Have you tried taking your setup out in your boat in an area that you know well (in good weather!) and trying it out?
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Old 20-07-2006, 01:05   #15
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Paul,
The satellite images I use have about 30 calibration points, and have been fine in comparison with the chart so far!
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