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Re: Map Projection Clarification [message #87614 is a reply to message #87613]

Tue, 18 February 2014 13:25

morganlsilverman
Messages: 46
Registered: February 2013

Member

On Tuesday, February 18, 2014 4:06:07 PM UTC-5, Phillip Bitzer wrote:
> Hi Morgan-
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> On Tuesday, February 18, 2014 2:42:25 PM UTC-6, Morgan Silverman wrote:
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>> I'm trying to set up a map projection using
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>> mapCoord = Obj_New('cgMap', 'Lambert Conformal Conic', Ellipsoid='WGS 84', /GCTP, limit=limit, $
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>> position=plotPosition, center_latitude=38.5, center_longitude=-77.5, STANDARD_PAR1=40, STANDARD_PAR2=-39). I honestly am just following examples I've seen but don't understand what each piece means and can't for the life of me find answers anywhere. At the moment I'm just getting a white screen when using mapCoord compared to cgMap_set.
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> Well, since you're using objects, you have to get into a slightly different mindset. The OBJ_NEW() command simply _initializes_ the object. You still have to draw it:
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> mapCoord->Draw
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> This invokes the Draw method of the object.
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>> Is there a list of different ellipsoid options to use?
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> According to the documentation for cgMap (https://www.idlcoyote.com/idldoc/maps/cgmap__define.html), it is basically a wrapper for MAP_PROJ_INIT : http://exelisvis.com/docs/MAP_PROJ_INIT.html

Thank you for responding. Oops forgot the Draw command. Well that certainly helps things. After reading more online I think I understand that the parallels are dependent on what type of map projection you use and how large an area you're viewing. Makes a little more sense I think. I'll have to keep reading about them to fully understand how to choose them correctly.

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[Message index]

		Map Projection Clarification By: morganlsilverman on Tue, 18 February 2014 12:42
		Re: Map Projection Clarification By: Phillip Bitzer on Tue, 18 February 2014 13:06
		Re: Map Projection Clarification By: morganlsilverman on Tue, 18 February 2014 13:25
		Re: Map Projection Clarification By: David Fanning on Tue, 18 February 2014 13:31
		Re: Map Projection Clarification By: David Fanning on Tue, 18 February 2014 16:25
		Re: Map Projection Clarification By: David Fanning on Tue, 18 February 2014 16:34
		Re: Map Projection Clarification By: morganlsilverman on Tue, 18 February 2014 16:39

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