don't understand scale

[Stephen Woodbridge]

Douglass,

Scale is the ratio of the real world extents of an image of your data 
compared to the physical rendered image of that data.

SO say for example lets say you display 10 miles of real world data onto 
an image that is ten inches wide. Then you scale is 1 in : 1 mile or 
1:63360 because 1 mi = 5280 * 12 inches

For displaying on the screen we figure 72 dot per inch. If you are 
trying to figure out how to set minscale and maxscale values, most of us 
  add

   <p>Scale 1:[scale]</p>

to our templates or get the scale directly from the mapObj->{scale} and 
print it on out web pages. Then as we zoom in/out if always shows the scale.

HTH,
   -Steve W.

Douglass Davis wrote:
> Ok, so the scale is relative to the units used in the mapfile.  I still 
> don't quite understand.  This example would help me a lot if any one 
> could explain it.
> 
> let's say I have a map with (fictitional units)
> 
> EXTENT 100 100 200 300
> 
> Now...  For example, what scale number will I have to use in zoomScale 
> to get a map scaled to exactly 100%.  Meaning, exactly the same map I 
> would get without scaling.  From that number I can get the other scales.
> 
> And can any one explain how they got this mathematically?
> 
> ---
> http://www.douglassdavis.com
> 
> 
> Douglass Davis wrote:
> 
>> I am using php mapscript, and i want to zoom in to a point.  I have 
>> two options:
>>
>> zoomPoint and zoomScale...  I understand zoomPoint, because it just 
>> zooms by a percentage.  But, zoomScale, I am not understanding.  It 
>> zooms to a certain scale, which is a double.  What does that scale 
>> represent? What is the scale relative to?  The docs don't really 
>> explain this well.
>>
>> The reason I wanted to do this, is because instead of  zooming in and 
>> out relative to the previous map's extent, it would be better if I had 
>> about 9 zoom levels, kind of like mapquest.  level 1 would show the 
>> states, level 9 would be a close up of the street.   But each of the 9 
>> levels would be a fixed zoom amount, relative to the size of the 
>> original extent in the mapfile possibly.   Is this difficult to do?
>>
>> -- 
>> http://www.douglassdavis.com
>>
>