Polygon Drawing Discussion

[edchuang (retired)]

Maybe the workaround is to draw the polygon points always onto the grid so that it won't offset after compilation. Workable ka?

[76gpsguy]

Maybe the workaround is to draw the polygon points always onto the grid so that it won't offset after compilation. Workable ka?

Bingo! You are right Bro edchuang. This is how I create the 24 bits grid in Grid-24.img.

This method only workable if you do not need to save your hard works (polygons) in mp file or you are going to get 5 decimal places accuracy coordinates. This accuracy is not good enough to show the 24bits coordinates well in img map and you will face the out of shape / position issue again.

I have explored on this before and the result shown that minimum 6 decimal places accuracy coordinate is required in order to have minimum effect of out of shape / position on map objects after complication. Now the question is how to create and save 6 decimal places (minimum) accuracy coordinates in mp file. This is impossible to achieve it in GPSMapEdit due to the limitation of the software.

There is a method to achieve this, but ........ very time consuming and tedious, will slowdown the progress of your polygon project tremendously.

The detail steps of this method is as follow:
1) Run GPSMapEdit and check “Snap to grid” under Tools->Option->Edit. This will enable you to draw map objects with coordinates exactly on grid. Please note that polygons created with Polygon:Strip & Polygon:Rectangle tools only have 2 or 4 coordinates on grid exactly and depend on the orientation of polygon.
2) Open a mp file and draw polygons as usual way. Please do not save the file.
3) Copy the 6 decimal places accuracy coordinates of the polygons by double-click->Elements->Edit and copy.
4) Create a new mp file (use any text editor) and paste the above coordinates here. Add the necessary information to complete this mp file. Save the file.
5) Close the file in GPSMapEdit without saving it.
6) Open the new mp file and compile it to img file. Please do not save the mp file in GPSMapEdit.
7) Open the mp and img files and compare the polygons. You will notice that these 2 sets of polygon almost perfectly match.

[76gpsguy]

So far has any solution for it ?

Yes, please refer to above posting.

[edchuang (retired)]

I have explored on this before and the result shown that minimum 6 decimal places accuracy coordinate is required in order to have minimum effect of out of shape / position on map objects after complication. Now the question is how to create and save 6 decimal places (minimum) accuracy coordinates in mp file. This is impossible to achieve it in GPSMapEdit due to the limitation of the software.

Bro 76gpsguy,
Sorry, after reading I am still Does that means If we draw the polygon corner points exactly on the grid point we will still have polygon run out problem after compilation to .img? Thanks.

[fancheng]

The detail steps of this method is as follow:
1) Run GPSMapEdit and check “Snap to grid” under Tools->Option->Edit. This will enable you to draw map objects with coordinates exactly on grid. Please note that polygons created with Polygon:Strip & Polygon:Rectangle tools only have 2 or 4 coordinates on grid exactly and depend on the orientation of polygon.

PLEASE BEWARE WHEN U USE SNAP TO GRID
When Snap to Grid option enabled, when u save u file, all u old coordinates (before Snap to Grid enabled) will snap to grid.
I tested before, all polyline alignment all gone.

Here I attached Bro sunn reminder

Bro Ko, Bro Chinwy,

I don't see any problem in the printscreen. Looks ok.

So congratulation in getting the full licence of GPSMapedit. Rules - make sure 'SNAP TO GRID' is unchecked & in Lat/Lon in Hddd.ddddd format.

Always make a habit to check.

Me, I have learnt it the hard way.

Regards

Tks for the reminder. My memory was starting to fail after not doing any mapping work for 4 months. I could remember your words of caution in the meeting re "Snap to grid " = OFF!!

I got worried and did not want to set in rubbish and need rework to the already busy mappers.

[76gpsguy]

Bro 76gpsguy,
Sorry, after reading I am still Does that means If we draw the polygon corner points exactly on the grid point we will still have polygon run out problem after compilation to .img? Thanks.

If all polygon corners are on grid then you will not have polygon out of shape problem. But you may not be able to make all polygon corners on grid if you use Polygon:Strip & Polygon:Rectangle tools. Please refer to below attachment for more details. Please take note that these polygons are drew using the above polygon tools. You also can test it yourself by using Grid-24.img.

[76gpsguy]

PLEASE BEWARE WHEN U USE SNAP TO GRID
When Snap to Grid option enabled, when u save u file, all u old coordinates (before Snap to Grid enabled) will snap to grid.
I tested before, all polyline alignment all gone.

Thanks for your advice.

[edchuang (retired)]

PLEASE BEWARE WHEN U USE SNAP TO GRID
When Snap to Grid option enabled, when u save u file, all u old coordinates (before Snap to Grid enabled) will snap to grid.
I tested before, all polyline alignment all gone.

Too late.

[76gpsguy]

PLEASE BEWARE WHEN U USE SNAP TO GRID
When Snap to Grid option enabled, when u save u file, all u old coordinates (before Snap to Grid enabled) will snap to grid.
I tested before, all polyline alignment all gone.

Too late.

Don’t need to , after compilation, your polygon coordinates will be shifted / adjusted onto grid by cgpsmapper compiler.

[alyem]

With the New Map MFMv120, now I have more idea and room to improve on the Polygon.
But not on the straight line or alighment.
More on the Polygon Mapping.



Thank you to all the mappers...
Thank you to Bro Antyong..
Thank you to Bro Sunn...