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Old 22-08-2014, 17:55   #1
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Google Earth

When I have created a KAP chart file from Google earth and open it in OpenCPN, how to I control which scale chart displays behind it?

I have several charts of a particular area, and when I zoom into my Google earth detail image/chart of say a harbor entrance, the chart displayed behind and around the image is usually a wide area chart, rather than the detail chart of the harbor area.

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Neil
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Old 23-08-2014, 02:04   #2
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Re: Google Earth

Quote:
Originally Posted by NeilW View Post
When I have created a KAP chart file from Google earth and open it in OpenCPN, how to I control which scale chart displays behind it?

I have several charts of a particular area, and when I zoom into my Google earth detail image/chart of say a harbor entrance, the chart displayed behind and around the image is usually a wide area chart, rather than the detail chart of the harbor area.

Thanks
Neil
I sounds like your GE-kap has the scale wrong. Go back and review how you converted the GE chart picture to a kap chart.
OpenCPN has no way of knowing the scale of a chart, other than the built in scale in a kap file. If this is wrong it will quilt with the wrong set of charts. Also....read up on quilting in the manual. Not all charts quilt together.

Thomas
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Old 23-08-2014, 15:46   #3
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Re: Google Earth

The google earth chart is correctly scaled and fits in the larger background chart with perfect registration.

Unfortunately OpenCPN is displaying a large area chart behind the image rather than a detail chart.

Neil
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Old 23-08-2014, 15:52   #4
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Re: Google Earth

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Originally Posted by NeilW View Post
The google earth chart is correctly scaled and fits in the larger background chart with perfect registration.

Unfortunately OpenCPN is displaying a large area chart behind the image rather than a detail chart.

Neil
Let us have a look at your GE chart. Compress and upload it here. Stick a .pdf at the end of the name. This should be OK if the file is less than about 550 kb.
Otherwise use a temporary web service.
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Old 23-08-2014, 16:44   #5
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Re: Google Earth

The Google image displays chart pib1.kap (1:30,351) perfectly registered to the large area chart 14820_1.kap (1:400000), rather than on the smaller area chart 14844_1.kap (1:40,000). I believe the smaller area chart covers the entire area the Google images does.

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Neil
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Old 23-08-2014, 16:45   #6
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Re: Google Earth

let me try that again - the file did not go through
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Old 23-08-2014, 16:50   #7
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Re: Google Earth

Trying the file again..
Attached Files
File Type: pdf pib_zip.pdf (433.8 KB, 37 views)
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Old 24-08-2014, 02:26   #8
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Re: Google Earth

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Originally Posted by NeilW View Post
Trying the file again..
Thank you!
The reason for your problem is that you are trying to quilt a Mercator chart (GE) with Polyconic charts (all other charts in Lake Erie )

From the OpenCPN manual
Quote:
Polyconic Charts, are quilted separately, and don't mix with Mercator or Transverse Mercator Charts
I did a quick and dirty thing and changed the projection to polyconic, without changing anything else. The chart now quilts correctly, but with warnings for poor Geo-referencing accuracy.

Check if GE2KAP has a option for creating polyconic charts. If not, talk to "phiggins" about it. This would be the correct way to solve the problem.

Your chart with my change:
pib1.kap.zip.pdf

Thomas
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Old 25-08-2014, 10:10   #9
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Re: Google Earth

Thanks.

It seems While most Lake Erie charts are Polyconic (and the Great Lakes in General) there are a few Mercator charts thrown in to - so I will have to take care which I include in my Chart Groupings.

How did you change the GE kap file from one chart type to another?

On another sort of related topic. When I zoom out I can see the red outline for each chart in my collection on the large scale chart displayed. I may have missed it in the manual, but is there any way to identify (and/or select) these charts other than scrolling through the chart icons at the bottom of the screen.

Thanks very much for your help. This is a great program and a great forum of helpful people.

Neil
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Old 25-08-2014, 10:34   #10
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Re: Google Earth

Neil...
The KAP chart file contains a text header and TIFF image. To edit the projection you just open it with a decent text editor (one that does not try to be smart and change the binary image part), change the text in the header, save and run bsbfix (from libbsb - Read, Write and Convert BSB charts) on it.

The charts displayed are selected automatically if they cover big enough part of the screen, there is no other way to "switch" between them but a) clicking on the chart bar or b) letting the chart selection logic kick in while zooming/panning.

Pavel
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Old 25-08-2014, 10:38   #11
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Re: Google Earth

Thanks,

I will play around with my other GE kap files and see how they come out.

Neil
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