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Boyd

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Jul 31, 2004
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Ben's Branch, Stephen Creek
Those are not "my" 24k and 100k maps! :D

You are using the NJGIN 24k and 100k maps, and their quality is terrible. I have no control over that, they are provided by the NJGIN servers. This is the very old USGS DRG (Digital Raster Graphics) imagery that was some of the first electronic versions of USGS maps and they have been discontinued by the USGS long ago. The quality has always been terrible for these, I would suggest not using them unless you have no other choice (my map only covers Southern New Jersey).

Here is my map

https://online.boydsmaps.com/#17/39.57548/-74.54328/pines1999
boyd.png


And this is the (horrible) NJGIN map

https://online.boydsmaps.com/#17/39.57548/-74.54328/njgin24k
njgin.png


My maps were created from the full resolution (level 16) scans of the final version of the 24k topo's from the USGS Historical Topographic Map Archive. More info here:


BTW, my map is also much higher quality than the ArcGIS 24k topo maps here on NJPB Maps, my map is on the left, the NJPB map is on the right



 
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icesailr

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Sep 27, 2020
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Manasquan, NJ
this shows my ignorance of and inattention to your site. I'm sorry to waste your time, but very glad for your reply. I did not pay attention to the headings of each map section and the fact that Your Own maps are all only under your heading (of course, as they should be). When I saw the heading in the GAIA map of "USGS" and then saw similar listings when I opened the section below yours, I thought those were the USGS to look for. My apologies. I didn't think to click on your 1999 in the pines map to find what I was looking for.
 

manumuskin

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Jul 20, 2003
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I think Thats the normal course of things that a 100K topo would have less detail then a 24 K topo since the 100 K covers four times as much area as a 24 K topo does,100 K is 100,000 inches on ground to one on the map while 24,000K is 24,000 inches on ground to one on map.@$ K has much more detail but covers much less area.
 
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Pan

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Jul 4, 2011
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Awesome maps! Too bad I can't get to use them to explore those wondrous woods anymore as I now live far away. I used to use big paper USGS maps that I coated with waterproofing (and didn't fold up very well anymore after the coating) , that and my compass.
 
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Boyd

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a 100K topo would have less detail then a 24 K topo since the 100 K covers four times as much area as a 24 K topo does
Was just looking at this again and you have described the difference very well, but this part is wrong. It's a common misconception, so I created the example below. The 100k topo actually covers sixteen times as much area as the 24k! Look at the grid squares on the 24k map, they are the same size in pixels as the whole 100k map. BTW, that's a 1-kilometer grid which is very cool - didn't know the USGS was using the metric system on these maps :cool:

100k-vs-24k.png


"Area" is a squared function, so (using round numbers) 96,000 divided by 24,000 is 4. But it's 4x as wide and 4x as high, so 4 x 4 = 16. When dealing with digital imagery, that also means a 24k map will require 16x as much disk space as a 100k map of the same area (although data compression might improve this a bit).
 
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