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Grid scale

July 27 2010 | 2 comments
Categories: Map Data


according to the blog:
http://blogs.esri.com/Support/blogs/mappingcenter/archive/2009/12/03/Mathematical-Relationships-among-Map-Scale_2C00_-Raster-Data-Resolution_2C00_-and-Map-Display-Resolution.aspx

If I have to generate a map 1:25000 how much should be the size of the grid?
How to calculate the value of 4000?
With the 30-meter DEM I can generate a 1:25,000 scale map?

Mapping Center Answer:

I am attaching a table that is still in progress -- once it is complete, we will write a blog entry about it.  You will see that for a map at a scale of 1:24,000, your best bet is to use 10m DEM data rather than 30m data.

I am not quite sure what you mean about calculating a value of 4,000 -- perhaps if you sent us some additional informaton, we could help you with this.

here is the value? posted by Alexander Pineda on Aug 13 2010 3:35PM
here is the value posted by Alexander Pineda on Aug 13 2010 3:34PM
In the simple case of a square cell digital elevation model (DEM), such 30m x 30m UTM grid cells, the optimal ground dimensions of the pixels on the map should be the same (or larger) than the DEM spatial resolution. For example, at a map pixel density of 4000 pixels per meter, the optimal mapping scale would be 1/x = 1 / (30 m/pixel × 4000 pixels/m) = 1:120,000 (or smaller). This recommendation, of course, is for large to medium scale mapping where there is minimal scale distortion across the map projection.
Not quite sure what you mean posted by Aileen Buckley on Mar 11 2011 3:42PM
We have tried to figure out what you mean about the 4000 value but we are still confused.

As we noted in a recent blog entry: An equation you can use that relates map scale expressed as a representative fraction(1/x), DEM cell resolution, and map display resolution is:

1/x = 1 / (DEM cell ground size [cm/cell] × map pixel density [pixels/cm]), so that 1 centimeter on the map represents x centimeters on the ground.

You can read more about this here: http://blogs.esri.com/Support/blogs/mappingcenter/archive/2011/02/28/dem-resolution-output-map-pixel-density-and-largest-appropriate-map-scale.aspx

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