Convert garmin .img pseudo-NT to non-NT? I know it's possible, but how?(SOLVED!!!)

**testlelelala** · 22nd August 2013, 04:45 AM

Originally Posted by Giomen

What about it?

Other than that, I have done some research on the deviation of China map
coordinates. Though there is no concrete result, you can follow it in this
article
[Only registered and activated users can see links. ]
My ultimate goal is to change the coordinates in place, i.e. change individual
bytes without recompiling the map. The cmdc tool is to generate the deviation
table. The gimgfixcmd tool fixes the deviation of a map.

...

The reverse engineering of the unlocking algorithm and the GMP section (aka the NT format by Garmin) are my work.

It is really work!

Originally Posted by Giomen

I do not write what it is saucer with blue border! But source code is very useful things sometime. We had big provocative discussion about non-NT and NT format on russian forum. Do the bible by John Mechalas have another analogue?

Originally Posted by catymag

It could be nice to hear
[Only registered and activated users can see links. ]
opinion about this matter

I also need that Wu Yongheng explain us what he means. I didn't understand what he said.
From what i see, gimgtools doesn't help us.
In [Only registered and activated users can see links. ]
He says:
"...Credits:
Most of the reverse engineering on IMG format was done by other pepole (listed
below). I just read their docs and code. The reverse engineering of the
unlocking algorithm and the GMP section (aka the NT format by Garmin) are my
work...."

But i don't see where in his utilities he reverse engineered the pdeuso-NT format, or even more, where, he reverse engineered the NT format as he is claiming.
It would be nice he accomplished that, it would be nice Wu Yongheng explain us.

**kunix** · 22nd August 2013, 06:23 AM

Originally Posted by testlelelala

The header size is located in the first two bytes of each header.
Example: When you found "GARMIN RGN" before that you see two bytes 7D 00 it means x7D which after conversion to decimal is 125 bytes.
Analog with LBL (xEC-->236 bytes), NET(x64-->100 bytes) and NOD(x3F-->3 bytes)
The only one "odd" is the TRE header that is larger that what you see in the first two bytes, because it could change with copyright info, nevertheless this extra info is not necessary, you could only grab the size that you get from the first two bytes.

I'm afraid it's not true. I've seen a map with GMP subfiles having some data (not copyright) beyond the standard header size for almost all headers (except 2, don't remember which ones), but before the next header. This map was an NT one, actually.

Originally Posted by testlelelala

But i don't see where in his utilities he reverse engineered the pdeuso-NT format, or even more, where, he reverse engineered the NT format as he is claiming.
It would be nice he accomplished that, it would be nice Wu Yongheng explain us.

See, for example, gimglib.c line 153, it parses GMP headers below.
Also function create_patch at gimgunlock.c line 95 should be able to handle NT map data.

Thread: Convert garmin .img pseudo-NT to non-NT? I know it's possible, but how?(SOLVED!!!)

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