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General Category => General Discussion => Topic started by: Forrest hunters on February 07, 2011, 08:33:53 AM

Title: Topo map scales
Post by: Forrest hunters on February 07, 2011, 08:33:53 AM
Can anyone tell me about the Michigan topo map that is 24k scale and the Northeast Topo United States Part 1 of 3 Map?  I think that maybe the NE Topo is 100K scale?  Can anyone confirm for me as I have both loaded onto my Oregon and may want to remove one of them.

Title: Re: Topo map scales
Post by: maps4gps on February 07, 2011, 09:02:04 AM
Scale in a digital product is not really definable like it is on a paper map.

What we refer to scale is related to the scale of the source date.

The data we use to build mapsets comes from various sources.  A data source itself may use data with more than one scale and sometimes does not even specify were the data comes from, etc.

There is also the question of how the 'scale' of digital source data compares with the scale of printed source data.

There are other concerns with the data source and sometimes the source data which is more 'detaild' is not overall the best to use.

That map author used the USGS NED (grided elevation data) with a 90 meter spacing.  Everyone else was using the NED dataset with 30 meter spacing.  Hence he used 1/9 of the points to build his contours which possibly looks more like 100k contours than 24k.  He also used a 20 foot contour interval for all 48 States; about 50% of the printed USGS 24k quads use a more detailed contour interval.

Anything specific which gives you this impression?
Use whichever one you feel is best for you needs.



Title: Re: Topo map scales
Post by: Forrest hunters on February 07, 2011, 09:09:54 AM
Thanks for the quick reply. 

Anything specific which gives you this impression?
BY my house i see 3 times as many contour lines in the Michigan Topo vs. the NE Topo maps.  Thats why I asked.  Love the feedback you have given me.  Its been a long time since I have my serveying class in college and i guess i dont remember as much as i thought i did.

Also the reason i asked was I have both on my Oregon 450 and I may dump one of them as I am getting in a lot of cases 3 duplicate POI in that folder and my start up time is around 45 seconds to a minute and think it may be because I have duplicate data there.

I think i would like to have just a road map loaded on my gps and then a topo overlay so i can view just roads if i want.  Is there a way to get ride of the duplicate POI if i do that?

 
Title: Re: Topo map scales
Post by: maps4gps on February 07, 2011, 09:46:58 AM
You could use my Planimetric - North Central and/or North East along with my Michigan contours20ft overlay mapsets.  In the contour overlay mapset I used a contour interval of 20 feet for the entire State to be consistent; thus it may only have half the number in the MI topo.
Two of the duplicate POI's may be coming from the MI topo as I included hydro POI's from both the USGS GNIS and NHD databases. 
Title: Re: Topo map scales
Post by: Forrest hunters on February 07, 2011, 10:26:47 AM
I am torn on which maps i want.  i like the 10 foot contour map but sometimes i think it makes it a touch cobbled.  Other times i think it is perfect and i am sure there is never a happy medium.  I think that having the duplicates may be slowing the unit down some though.  What do you think?  If so I may dump the others for MI and just use your Mi topos which are awesome.
Title: Re: Topo map scales
Post by: jbensman on February 07, 2011, 11:13:52 AM
What do you mean by, "getting in a lot of cases 3 duplicate POI in that folder"  particularly "folder"?

What I don't like is when you use where to, geographic points, it will look from the maps I made (MY POIs and My Trails) and the built in 100K topos even though I have it disabled.  So I get multiple POIs for the same thing.  I wish it would only search ACTIVE maps!

You are not dispalying both topos at the same time are you?  Only enable one of them at a time.

I've got all kinds of maps loaded on my 550T (which works just like you 450) and I have never noticed it slowing the GPS down.  However, sometimes there is a slight delay when panning when there is lots of stuff on the screen like a high concentration of topo lines. 
Title: Re: Topo map scales
Post by: Forrest hunters on February 07, 2011, 11:35:27 AM
jbensman, you are correct in my where to folder.  I do only have one map active at a time unless it is an overlayment map. 

My only slow down is when i turn it on it take 45 seconds to a minute to get to the home page.

Thanks,
Title: Re: Topo map scales
Post by: Boyd on February 07, 2011, 12:11:22 PM
With just about every Garmin unit I've owned (LOTS of them  ;) ) I've noticed an additional delay when you add maps. I think the unit builds some kind of index when it starts up maybe? I have a 16GB card that is completely full of BirdsEye imagery. When I insert that into my Oregon 400t, startup takes FOREVER - several minutes. Of course, that's probably something different than vector based maps...
Title: Re: Topo map scales
Post by: Forrest hunters on February 07, 2011, 04:37:53 PM
I did a little test and without card in it is 12 seconds and 47 seconds with 4gb card with about 1.4gb worth of maps loaded on it. Does that seem too long?
Title: Re: Topo map scales
Post by: jbensman on February 07, 2011, 10:06:48 PM
No.  You cannot wait another 30 seconds????????
Title: Re: Topo map scales
Post by: Forrest hunters on February 08, 2011, 08:10:04 AM
I can wait that long.  It just seems others are getting their units to start up a lot quicker than that with a lot more loaded on the cards.

I will see what speed my card is and maybe get a quicker card.

Title: Re: Topo map scales
Post by: Boyd on February 08, 2011, 08:46:35 AM
Somewhere in one of Garmin's FAQ items I recall they said that the larger the SD memory card, the slower the startup time. Not sure why this would be unless maybe it does some kind of sector scan at startup? They implied that the card size itself was an issue, and not the number of maps it contained.
Title: Re: Topo map scales
Post by: Forrest hunters on February 08, 2011, 10:46:04 AM
Boyd,

Thanks for the input.  Are you on every forum for gps there is?  I see your screen name everywhere. 

I checked at lunch and my card is a 4gb and class 4.  I wonder if different manufacturers are different speeds?

Thanks,
Rob
Title: Re: Topo map scales
Post by: Forrest hunters on February 09, 2011, 07:05:44 AM
Last night I did some testing with loading the maps. Below is a spreadsheet of what I did and the boot times there after. I did shut it down and turn it on 3-4 times after loading each map to make sure everything was good before i took these times. Does this sound like about what everyone else is getting. Do you think if I broke some of these larger files into a few smaller ones but still have all that info on there that it would speed things up? Maybe me being a newbe I am loading to big of files on there at once.


                                        start up time          file size
no card                             12 seconds
michigan topos                  14 seconds           146,536 kb
other michigan topo           14 seconds             59,299 kb
US states and counties       14 seconds              1,918 kb
US P North Central             25 seconds           335,832 kb
US P North East                 32 seconds            282,872 kb
NE Topo Part 1                  46 seconds            642,656 kb
Total 1,469,113 kb


Disk reads 1.40gb used 1,504,444,416 bytes

2.28gb free 2,452,291,584 bytes

3.68 gb capacity 3,956,801,536 bytes

Thanks again.
Title: Re: Topo map scales
Post by: Boyd on February 09, 2011, 09:01:09 AM
My *guess* would be that it's related to the number of map sectors and not file size. The one test that you didn't do would be to have a blank formatted card in the slot. I guess it couldn't make much difference though, because the small map file only resulted in 2 additional seconds of startup.

Nice science project there - thanks for posting your results!
Title: Re: Topo map scales
Post by: Forrest hunters on February 09, 2011, 09:30:23 AM
Boyd,

i actually did test with the blank card in and it was the same as no card.  How can i tell how many map sectors i have loaded?

thanks,
Title: Re: Topo map scales
Post by: maps4gps on February 09, 2011, 09:55:59 AM
I do not know if you can tell after they have been upload to the GPRr; however, MapSource gives a total of both the number of quads/segments selected and the total file size below the window on the left which lists the quads/segments selected.
Title: Re: Topo map scales
Post by: Forrest hunters on February 09, 2011, 10:04:46 AM
maps4gps,

I can figure that out by just selecting the number in each again.  Is there a limit as to how many you can put on one map or a total number allowed in the unit?  Somewhere seems to me i read a maximum you can put in.

Title: Re: Topo map scales
Post by: maps4gps on February 09, 2011, 10:31:15 AM
On the OR (also CO, DK, 78, 62) the limit is 4000 quads/segments total for the GPSr.  The FAT32 formating of the micro memory card limits an individual xxxx.img file to 2Gb.  There have been posts on forums.groundspeak.com where 16Gb cards have been filled and work fine, with verbage that a 32Gb card will also work; however, I do not recall anyone posting that they are using a 32Gb card.  I recall Boyd is using a 16Gb card with most of it used for Garmin's Birdseye imagery.
Title: Re: Topo map scales
Post by: Forrest hunters on February 09, 2011, 10:44:07 AM
Just added a little more info to the list. Added how many segments each map has.

michigan topos 14 seconds 146,536 kb 130 segments
other michigan topo 14 seconds 59,299 kb 44 segments
US states and counties 14 seconds 1,918 kb 2 segments
US P North Central 25 seconds 335,832 kb 330 segments
US P North East 32 seconds 282,872 kb 268 segments
NE Topo Part 1 46 seconds 642,656 kb 463 segments

Total 1,469,113 kb 1237 segments

I think i may start a new thread here and in gs just talking about this and see what others can paste about the amount of info they are loading and what kind of times they are seeing.

Title: Re: Topo map scales
Post by: Boyd on February 10, 2011, 08:23:03 AM
One of Garmin's FAQ's states that you can only have 4GB total mapping installed on your GPS. There seems to be a lot of conflicting info on this out there. Personally, I question that because it would be very limiting on a unit like the Oregon 450t that already has nearly 3GB with the pre-installed maps.

Quote
What is the largest SD/microSD card supported by an expandable memory device?

01/25/2011

There are several products within the Outdoor and Fitness families that can accept expandable memory cards in SD or microSD format. These cards, for some devices, can be used to store active track-log data, however, all expandable memory devices can utilize the additional memory to store MapSource products.

There are limitations to the size of SD/microSD card used and to the number of detailed mapping segments that can be recognized by a device.

If at the most recent unit software version, these limitations are:

    * There is no limitation to the size of SD/microSD card used but the device will only recognize 4GB of detailed mapping
    * Each expandable memory device will be able to recognize up to 2,025 detailed mapping segments

If 2,025 detailed mapping segments are loaded to an SD/microSD card but does not reach 4GB worth of data, the unit will not show any more detailed mapping than what is provided by the mapping segments.
Title: Re: Topo map scales
Post by: maps4gps on February 10, 2011, 05:22:44 PM
Previous information indicated the segment limit had be increased to 4000 segments.

Is Garmin's 1/25/2011 statement about the 'most recent unit software version' will recognize '2025 detailed mapping segments' on each expandable memory device indicating a reduction of capabilty with the latest software, or that the 4000 segments was actually a total of 2025 on the memory card and 1975? on the GPSr's internal memory?
Title: Re: Topo map scales
Post by: Boyd on February 10, 2011, 06:13:52 PM
Yeah, I think that's just plain wrong. The Oregon, Nuvi, Colorado, Dakota, etc. all recognize 4,000 segments. Like I said, there's a lot of confiicting information out there...