Charts II: NGA - 2700 Charts

[Viking Sailor]

Originally Posted by HappySeagull

...and that's where (over the the old buoy) I'll use the "X" icon I'm making...and this "correction" gpx would show on the vector charts too (CM93's would need be position-calibrated properly with OpenCPN to have the X right on the old buoy in them)
Oh,there's problems in my thesis,for sure.long Pipelines or powerlines would be more troublesome as a big icon laid in pieces than just drawing on a charttiff...but still possible.

The correct thing to do is to correct the charts. This way everyone ends up with a good set of free charts. Now, that would be truly worthwhile!

[LeaseOnLife]

I just checked on OpenCPN.info (English) and we are only missing 8 out of 2725 charts, most likely due to missing tiles on the NOAA/NGA server.

There are now thumbnails of each chart, clicking on the thumbnail loads a larger image, but not the whole ## Mbytes chart. VERY NICE!

Can't wait to get going on some calibrations....

[Netsurfer]

Originally Posted by LeaseOnLife

There are now thumbnails of each chart, clicking on the thumbnail loads a larger image, but not the whole ## Mbytes chart. VERY NICE!

Yes, happy that you like it.
The thumbs are not made from the uploaded full-size images but simply downloaded image 0-0-0.jpg of each file.
Same for the larger view (which is zoom level 2)!
The "preview" images are menaly meant for easy & fast checking if a chart is a "plain/normal" one or if it has additions like plans etc.

If a thumb or zoom level 2 image is "corrupted" (not showing the complete chart) this does not mean that the full-size image is corrupted, too! It's caused by missing or corrupted tiles for the appropriate zoom level.

Can't wait to get going on some calibrations....

Work in progress ...

BTW: I am actually downloading the last missing chart images for region 3 - 38260!

Gunther

[Surveyor]

38260 is missing a tile. Does anyone look at the github failed download wiki?

[Netsurfer]

Originally Posted by Surveyor

38260 is missing a tile.

Correct!

Does anyone look at the github failed download wiki?

Just after your post ...
Too many places to gather the info from ...

I propose to use the chart anyway (with a notice that 1 tile is missing), because we can do all the rest (like calibration) and if someone reports it to NOAA maybe they correct the error and we just need to fetch the missing tile ... which is btw 7-36-37.jpg!

Gunther

[Surveyor]

I am sorry if I sound irritated

I do agree too many places to look. Going forward we should make it easier to communicate in one place. It might make the difference in the next phase taking a few months rather than a few years.

[cagney]

I have just uploading 25525, as it is , with the top missing, simply no tiles there.
The approaches to "Havre de la Trinite" is missing, otherwise still good info for cruising the East Coast of Martinique. Hopefully NGA will publish the missing tiles. We can still make a kap chart of whats available, with a bit of manual job.
Thomas

[r.fairman]

can we download an original jpg from the site. I may want to do this to calibrate locally and run some ideas locally Can the NGA catalogs be made available here or do we download them from NGA Talking chart numbers is very efficient but means little when deciding coverage

Once the calibration is complete OpenCPN calls out for an on demand search/ chart download feature for a right clicked area. to pull a chart from our archives

richard

[Netsurfer]

Originally Posted by r.fairman

can we download an original jpg from the site. I may want to do this to calibrate locally and run some ideas locally Can the NGA catalogs be made available here or do we download them from NGA Talking chart numbers is very efficient but means little when deciding coverage

Sure you can.
All uploaded images are available from: ftp://ftp.weizterfish.com/
or use any FTP client you'd like to.

Once the calibration is complete OpenCPN calls out for an on demand search/ chart download feature for a right clicked area. to pull a chart from our archives

Good idea.

Gunther

[LeaseOnLife]

Originally Posted by cagney

I have just uploading 25525, as it is , with the top missing, simply no tiles there.
Thomas

Could you describe how you do that? The ruby script just fails and does not create an image... Maybe use the wiki for now.

https://github.com/ngacharts/ngacharts/wiki

[r.fairman]

Notice to mariners

Is there some way we can Automate or semi automate the application of NTM,s I estimate there are well over 10,000 NTM's to apply Perhaps NGA would pay me as a project to do the work.

Each chart has a link to its NTM's
All NTM' are in the same format essentially a five column table
Column 1 Chart Number
Coumn 2 Action (add replace etc)
Column 3 Description
Columns 4 and 5 coodinates

It is a simple process to copy and paste into an Excel spreadsheet

Can a script parse the spreadsheet to take you to the correct location on the chart. Either for a layer overlay (which i do not support) or a manual correction to the image file. We can extract the image from the calibrated kap file to apply cahges but the problem is how do we easily apply the changes at the exact coodinates given. I know we can use of fashioned plotting method but that is going to be very time consuming.

We could build a database of common nav object as photoshop objects to apply to the correct coodinates.

Just an idea for comments I can think of ideas but do not have the skills to implement. Could this be a NTM plugin

regards

Richard

[r.fairman]

GPS Visualizer will convert the NTM spreadsheet to a gpx file to display the coordinates of the NTM' on a chart in OpenCPN Is there an offline version of this tool

[r.fairman]

As a test i just converted 30 NTM's changes for a single chart to 30 waypoints. Took about 10 mins.
Just cannot get GPS visualiser to put the description of the change needed as the name for the waypoint for display on the chart

Method
1.Copy and paste a full set of NTM's for chart into excel
2.Remove umwanted colums and rows
3.Added header name,desc. latitude longitude.
4.Saved as 97 version spreadsheet
5.Converted to gpx with GPS viualizer
6.saved GPX file
7. Imported GPX file into OpenCPN

if i view the waypoints over an upto date cmap 93 chart they line up with upto date nav objects obstructions etc that do not appear in the NGA chart

regards
Richard

[HappySeagull]

There are,anyways problems with the NTMS as direct gpx positions...in the example you see the NTM(for 18419) wreck on this CHS Victoria BC chart...note that it is to the EAST and a bit NORTH.This is as it would be,given NAD27 datum...
note also this datum note from the 18419.jpg chart...important but not so useful for "calibrationists"... it looks as though they don't know (or care to say)that it's NAD27 ...



Still,the positions of NTMs referred to suit the paper chart just fine for the "redo-the-graphic" camp(but I still wonder how many out there are able to edit an 800 mb image),while the gpx-ers (just me apparently)must adjust positions.
hmm

[r.fairman]

If i pull the image from a calibrated kap chart i get an image file of about 3.5 Mb which can be worked with by most photoshop type programs The idea is to apply the NTM and convert back to a kap using the original calibration

Layers is one route
Apply ntms graphically is another

i repect your right to be wrong LOL

richard