Applying Notices to Mariners (NTMs)

[r.fairman]

I hope opening a new thread about this subject meets with the forums approval. Aplying NTM's to existing calibrated charts is such a big, and important subject it warrants its own thread.

As a starter here is a general outline of my method of applying NTM's to a NGA chart of Marmaris Turkey

1. Navigate to the NTM for your chart on the NGA Site
2. Copy and paste the complete list of NTM changes into Excel
3. Unmerge all cells
4. Add a row at the top of the table with the appropriate headings Name, Desc latitude, longitude
5. Save the spreadsheet
6. Use GPS Visualizer to convert the Excel file to a gpx file
7. Open the GPX file in OpenCPN
8. The NTM changes are displayed on the chart as waypoints.
9. If you just want to use the GPX file to apply the NTM go though the waypoints and apply the appropriate waypoint symbol
10. If you want to apply the NTM graphically to the chart proceed as below
11. Using imgkap extract a header file and a png file from the chart .kap file
12. Open the png image in program such as photo paint or photoshop and display at 100%
13. Display the calibrated chart in OpenCPN at 100%
14. Use a utility such as Exact Mouse to display the x y coordinates of the mouse pointer
15. In photosop adjust the display to show an area where a ntm change or addition is needed
16. Position the mouse cursor over a distinctive land mark or lat long crossing point and note the x y coodinated of the pointer
17. Alt tab to OpenCPN and position the mouse cursor over the same landmark Drag the chart so that the x y coodinates are the same as the one you noted.
18. Open CPN and Photoshop are now displaying the chart and the image at the same zoom level and same position on the screen
19. Position the mouse cursor over a GPX way point created for the NTM as described earlier
20. Alt tab to Photoshop and the cursor will be at the correct position on the chart image.Note the xy coodinates.
21. You can now open or import an image file for the nav object and place it exactlty at the correct position on the cahrt image
22. Repeat this for all the NTM changes or additions
23. Save the file
24. Convert the png back to a kap file using the header previously created by Imgkap
25. To QA your results open the chart in OpenCPN
26. Display the GPX waypoints and ensure they overlay the nav obeact you have added to the image file
27. With care you an achieve an accurcey of 2.5 meters using this method

This may appear long winded but I applied a 30 point NTM in GPX and the chart image in 1 hour.
This procedure is crying out for automation but that is beyond me I have already suggested a NTM plugin that could use imgkap and imagemagick to do a lot of the tasks

regards

Richard

[r.fairman]

Does anyone have a complete set of nav objects as Gifs with transparent backgrounds. It would be nice to have such a set so if and when NTM's are applied we all use the same images. The nav object displayed in Cmap 93 seem to look the best if there is way to pull them and save as gifs They could be used a GPX/layer NTM's and NTM's applied to the chart image. They couls of course be converted to xpm's to use as usericons or later incorporated in OpenCPN a waypoint icons.

regards

richard

[nohal]

Richard...
My editor for the rasterization rules (OpenCPN - Rasterization Rules Editor - Redmine) can save the symbols as PNG and JPG.
I've added this possibility when the French guys were writing their tutorial, but am not sure whether they used the symbols there or not.
I will make it export all the objects automatically when I have a little time after the weekend - still will be less time consuming then if you have to do it manually one by one.

Pavel

[Surveyor]

It would be time consuming yet very nice and neat to somehow use the symbols in Chart No. 1.

Pavel's program looks useful.

I am going to explore using Vector Magic. I have the stand alone desktop version and use it often for other things. I will post a sample tonight so you can judge it.

It is pretty simple and would not require any artistic skill. Cut the symbol from the source, drop it into Vectormagic, it vectorizes and gives you options on color and smoothing and allows for the deletion of any background. Fast, efficient and the symbols would be nearly identical to the source.

If it works out, I would be willing to help platoon the symbol creation with whomever is willing. I would do this no matter what technique we end up using.

[r.fairman]

UPDATE

Just found that NGA has a query function
at

Maritime Safety Information

Wherby you can download a complete set of NTM' s for a particular year for all charts in their catalog.

I just downloaded a complete year as a tab delimited text file. I imported to Excel and added headers (the last row of the spreadsheet is numbered 70857

I used to convert to GPX with GPS visulizer and imported to OpenCPN

Route manager took some time but displayed all the waypoints


I now have waypoints created for all NGA chart NTM's for the year 2010

Should naw be possible for someone to create a mega GPX file or a series of GPX files for all years from 1999 to 2011 for all of the 2700 NGA charts. This should be stored with the original charts and be available to all Someone clever could organise them in to regions

Does opencpn have a waypoint limit. Route manager and opencpn now runs very slow as it loads the gpx data

[r.fairman]

sorry here is the GPX file for 2010

I supply it here for your reference DO NOT load to OpenCPN as it will slow down openCPN significantly You use at your own risk

Cannot upload the Excel spreadsheet as it exceed the forum size limit

[HappySeagull]

Nice work,richard!wow that file looks very cool in Gpsutility...it looks like I can easily chop it up into 4 zones by clicking a few buttons... Tropics North,Tropics South,NorthLat,South Lat and EAST/WEST?

[r.fairman]

I don't thing GPS Visualizer is converting the full set of waypoints in the download from NGA . When i look in Excel there seems to be more wayponts than in the final GPX file. If you import the GPX into OpenCPN it generates about 2700 waypoints

[HappySeagull]

Richard,that's too bad but fits and starts are par for the course,eh?Me,I've been tooling around and managed to sort the file posted to North and South Tropics,N+S Temperate and split again to E+W so they show up fine in OpenCPN including notes.Had my own software issues to do it but,hey
Try EasyGPS ...It seems best yet to sort,cut and paste the GPX...
PS just clicking the(header?) buttons sorts as to lat lon and so forth

[nohal]

richard and others....
as promised all the 716 bitmap symbols for navobjects exported and available for download as a zipped package at https://github.com/downloads/nohal/R...bols-2.5.0.zip
A little preview:


Pavel

[r.fairman]

wow Thanks pavel

[r.fairman]

I am back working on the auto application of NTM's to the NGA charts I have the Nav Objects sent by Nohal but i cannot find some cardinal marks I can only find a N cardinal mark not the W E or S Does anyone know the total of Nav Objects used by cmap 93 I have 716 are there more

Richard

[nohal]

Richard...
I'm not exactly sure if I understand. There's quite a lot of cardinal symbols:
BCNCAR01-04 vectors nad BOYLAT01-04 vectors are used in simplified mode and not part of the set I posted (as well as the vector top shapes TOPMAR05-08 and TOPMAR25-28),
all the bitmap symbols for buoys and beacons OpenCPN can use to display a chart are in the archive:
BCNGEN68-71, BCNTOW68-71, BOYCAN68-71, BOYCON69-72, BOYPIL68-71, BOYSPH68-71, BOYSPR68-71, TOWERS68-71
I'm not aware of any object type where we have drawn just the north variant...

Pavel

[r.fairman]

The chart i am trying to auto apply NTMs needs cardinal marks added here is how they appear in cmap93

[sailorF54]

Originally Posted by r.fairman

I am back working on the auto application of NTM's to the NGA charts I have the Nav Objects sent by Nohal but i cannot find some cardinal marks I can only find a N cardinal mark not the W E or S Does anyone know the total of Nav Objects used by cmap 93 I have 716 are there more

Richard

Mostly, cardinal marks are made of two kinds of objects: a colored shape (spar, buoy, tower...) with the relevant colors and a suitable top mark.

There are many, many, many... thousands of POTENTIAL nav objects in CM93, as they are described by features. See pics



Thanks mostly to Pavel (Nohal) and a few co-workers the most frequent feature combinations have a bitmap rendering. If not, a default shape/color, possibly vector (i.e. not bitmap) is applied.

BTW, the top marks are drawn as vectors (i.e. they are not bitmaps)