North America 2gb map question

[blueberry61]

Quick question that's been bothering me for a while. I have a 920 which originally came with the 'North America' map. When I subscribed to the map update service last year TT customer service recommended upgrading with the 'North America 2GB' map. So my question is what exactly is the difference between the 'North America' and 'North America 2 GB' maps? (On the TT website it says the ?North America 2 GB? is modified/simplified?). TT customer service told me the difference is compression, the coverage and detail is the same and the 2GB map is compressed to fit devices with 2GB memory. But if there?s no difference why have 2 different versions of the same map, they could just have the 2gb version? Should I switch to the ?North America? map from the 2GB version?

 

[mikealder]

Secondary details such as rivers, coast line, woodlands etc will be far less defined on the 2GB map as will the built in POI files otherwise the road mapping itself will be the same. That said you might notice slight differences with two devices running different maps such as the number of points on the road when cornering as reducing the number of points reduces file size but does alter the display away from a nice smooth progression around a corner to a more step change - Mike

 

[coupable]

the go 920 comes with 4gb of internal memory...if your map is working fine why buying a new one?

 

[mvl]

Go with North America. The POI file on the 2GB is severely reduced from the file on the full "North America" map. There should be loads of space to fit the full sized map, and if not you can store it on an SDHC card in the Tomtom.

 

[blueberry61]

Thanks guys. So TT were not correct to say it is just about compression!

Is it still possible to use a POI data file from the "North America" version with the 2GB map - I think I have downloaded this from the TTForums site previously?

 

[dhn]

Yes it is...........but to play safe make an Explorer backup of your map file prior to overwriting with the larger poi.dat file (and crpoi.dat file as well)

 

[mvl]

If you copy these files, you also should copy the "brand" folder. If you don't your icons will be for the wrong stores.

 

[nomenclator]

This is not making sense to me. Here is TT's page describing the "regular" map. And here is TT's page for the "modified to fit devices with 2 GB memory" map. Note that the 2gb map is slightly larger. The regular map is 1641 mb, and the 2 gb is 1694 mb.

If the 2gb map is "severly reduced from the file on the full North America map" then why is it larger?

And why does TT describe both maps as "modified to fit devices with 2GB memory." And are the regular maps meant for devices with less than 2gb memory, or for devices with more than 2gb memory? If the regular maps are made for devices with more memory, why is it smaller?

 

[nomenclator]

If my device can use the "regular" map, does that mean I have a device with more than 2gb, or less than 2gb?

 

[nomenclator]

Also, I have an XL 335S. TT Home's update and restore feature lists the new map it wants to update my device with, as having 1641.4 mb. This is the size of the "regular" map. Yet TT Homes "magage your device" page lists "device memory" as 1958.5 mb - slightly less than 2 gb.

Since both maps are very close in size, there would seem to be plenty of room on my device for either map.

All this is making very little sense to me.

 

[dhn]

Your model has 2 gb storage. TomTom does not make it very clear in its descriptions of maps as to why the size differential. The 'normal' map is usually only available for units with 4 gigs of storage. These models are few and far between these days.

The 'normal' map has a stronger compression algorithm, as I understand it.

The map designed to fit the smaller memory sized units usually comes with fewer pois in the data set and less detail for non navigational areas like rivers, etc. As well, roads that are actually curved may appear straighter with fewer segments on the map as fewer segments = less space needed.

 

[nomenclator]

dhn, so why is the 2gb map listed as being actually a bit larger than the regular map. And why are both listed as being less than 2gb, and very close to the same size?

 

[dhn]

That's not what I'm seeing.........

Go to the TomTom US site and select maps to buy. Select your model as being a 930.

Now then, you can choose the North_America map which is 1841 mb or the (smaller) North_America_2GB map which is 1694 mb.

See here:
TomTom, portable GPS car navigation systems

Don't forget, the amount of real estate expands as the compressed map is uncompressed during installation. The larger (1841 mb) map would 'hit the wall' if you could even get it offered to you for a 730 model with just 2 gigs of internal storage.

 

[nomenclator]

Indeed, DNS, if you select the GO 930, you get the numbers you said, but if you select the XL IQ Routes Edition / 340 (which is the model that comes up when I put my serial number into the box at the right of the page, even tho my model actually labeled XL 335S - which I understand is the same hardware as an XL 340 but with a North America (US and Canada) map, instead of a US, Canada, and Mexico map), you get the numbers I said. Just click on the links I included in my first message. Also note that the US, Canada, and Mexico map, is being listed as 1696.6 mb, only 2 or 3 mb larger than the US and Canada map. I suppose there may be an error in the numbers being listed.

 

[nomenclator]

Also note that for the XL with IQ routes model, the "non" 2gb map selection has a descriptive paragraph describing it as being a 2gb map.

 

[nomenclator]

This is still not making sense. I have an XL 335S with less than 2 gb of internal mem, and I recently did my 30-day map update. The map I was offered, and that I downloaded, was the 850.2784 "regular" version of North America, which tt home Add Maps[/B ]says is on my device, and has 1644.9 mb, and not offered map 850.2781, the 2 gb version, which tt home Add Maps[/B ] says is "online," and say that I can "buy" it, by pressing the Buy button, and says that it is 1694.1 mg - slightly larger than the regular map.

Why was I offered the regular map if I have a 2gb device? Why is it smaller than the 2gb map

 

[dhn]

It's confusing, I agree......and I give up trying to figure out what Home shows anymore and why.

Suffice to say that if the map you downloaded installed on your unit ok, then you have the correct one.

Now, make an Explorer backup of the unit's contents.............

 

[mvl]

Why was I offered the regular map if I have a 2gb device? Why is it smaller than the 2gb map

There are three flavors of maps.

The "North America" map (on the GO 920/930) includes full maps AND speech recognition data.
The "North America 2GB" map (on the GO 720/730/740) includes maps with reduced POI, but keeps the speech recognition data.
The "North America P" map (on the XL335/XXL535) includes the full maps, but doesn't have speech recognition data since those models don't have microphones.

The size of the speech recognition files is what is making the total map size not make sense.

 

[nomenclator]

"Now, make an Explorer backup of the unit's contents."

Goodness gracious. That will take 45 min.

I made a complete backup of the TT internal drive, to my Backup Drive, just before downloading the new map. Since the new map was first downloaded to C:\Documents and Settings\Ted\My Documents\TomTom\HOME\Download\complete\map\North_America (on my main drive), before being extracted to the map folder on the TT, I therefore have a backup of the new map, on my computer. There is a file named North_America_P.zip there. TT home lists this zip file as being able to be restored to the TT. So I think I will be alright, until I get around to making another complete explorer backup, of the TT internal drive, in a week or so, to my backup drive.

Of course, I ought to back up the zip file to my second hard drive, my backup drive, so that I have 2 copies of it on my computer, before I do the following:

I tend to do daily backups of all my data files, and tend to do complete images of my entire hard drive once every few months.

 

[nomenclator]

Gosh, making a complete image of my entire hard drive, onto a second hard drive (sata drives, both in the same computer), hardly takes any longer than making an explorer copy of the TT internal flash!