Landscape Rotation - Revision history

Matthewg42 at 14:03, 2 December 2008

2008-12-02T14:03:40Z

Matthewg42 at 13:48, 2 December 2008

2008-12-02T13:48:44Z

Matthewg42 at 13:38, 2 December 2008

2008-12-02T13:38:53Z

Matthewg42 at 13:22, 2 December 2008

2008-12-02T13:22:49Z

Matthewg42: New page: When you make a landscape, you may want to orient some part of the image towards North or some other bearing. For '''spherical''' type landscapes (the formal name for this sort of panoram...

2008-12-02T13:19:02Z

New page: When you make a landscape, you may want to orient some part of the image towards North or some other bearing. For '''spherical''' type landscapes (the formal name for this sort of panoram...

New page

When you make a landscape, you may want to orient some part of the image towards North or some other bearing.

For '''spherical''' type landscapes (the formal name for this sort of panorama is a '''equirectangular''' panorama), you can use the following procedure for calculating the rotation needed. The rotation can be specified using the '''angle_rotatez''' setting in the landscape.ini file.

http://porpoisehead.net/misc/calc_landscape_rot1.png

In this image, there is a tree. Let's say you want this tree to appear at bearing 0 degrees in Stellarium (due North).

First, you need to calculate the distance from the left side of the landscape image to the tree as a fraction of the total image width, and then use these numbers in the following formula:

270 + b - ( 360 * x / X )

where:
*b is the bearing you want to have the chosen object, in degrees. Use 0 for North, 90 for East etc.
*x is the distance in pixels from the left side of the image to the object you want to align.
*X is the horizontal image size.

For example, here's the landscape image again, with some measurements:

http://porpoisehead.net/misc/calc_landscape_rot2.png

Putting the figures in the equation:

270 + b - ( 360 * x / X )
= 270 + 0 - ( 360 * 364 / 512 )
= 14.06

If the result is outside the range 0 ... 360, you should add or subtract 360 to bring it into this range.

The figure of 14.06 should be put into the landscape.ini file like this:

[landscape]
name = Test
author = Matthew
description = Test landscape to demonstrate alignment
type = spherical
maptex = image.png
angle_rotatez = 14.06

Note that the landscape image I am using in the example will work, but it's not a very good landscape image, so you might want to try this with a better panorama. The moon landscape which comes with Stellarium is a good one to practice on. As an exercise to check you know how to do it, consider applying a rotation to the moon landscape, having the astronaut due South. Check your answer [[Landscape_Rotation_Exercise_Solution|here]].

← Older revision		Revision as of 14:03, 2 December 2008
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	Check your answer [[Landscape_Rotation_Exercise_Solution\|here]].		Check your answer [[Landscape_Rotation_Exercise_Solution\|here]].

−	[[Category:Landscapes]]	+	[[Category:Landscapes]][[Category:Customization]]

← Older revision		Revision as of 13:48, 2 December 2008
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	Check your answer [[Landscape_Rotation_Exercise_Solution\|here]].		Check your answer [[Landscape_Rotation_Exercise_Solution\|here]].
		+
		+	[[Category:Landscapes]]

← Older revision		Revision as of 13:22, 2 December 2008
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	angle_rotatez = 14.06		angle_rotatez = 14.06

−	Note that the landscape image I am using in the example will work, but it's not a very good landscape image, so you might want to try this with a better panorama. The moon landscape which comes with Stellarium is a good one to practice on. As an exercise ~~to check you know how to do it~~, ~~consider applying~~ a rotation to the moon landscape, having the astronaut due South. Check your answer [[Landscape_Rotation_Exercise_Solution\|here]].	+	Note that the landscape image I am using in the example will work, but it's not a very good landscape image, so you might want to try this with a better panorama.
		+
		+	The moon landscape which comes with Stellarium is a good one to practice on. As an exercise, apply a rotation to the moon landscape, having the astronaut due South (the astronaut who is in the distance, not the shadow in the foreground).
		+
		+	Check your answer [[Landscape_Rotation_Exercise_Solution\|here]].

@@ Line 1: / Line 1: @@
 When you make a landscape, you may want to orient some part of the image towards North or some other bearing.
-For '''spherical''' type landscapes (the formal name for this sort of panorama is a '''equirectangular''' panorama), you can use the following procedure for calculating the rotation needed.  The rotation can be specified using the '''angle_rotatez''' setting in the landscape.ini file.
+For '''spherical''' type landscapes (the formal name for this sort of panorama is a '''equirectangular''' panorama), you can use the following procedure for calculating the rotation needed.  The rotation can be specified using the '''angle_rotatez''' setting in the landscape.ini file (note that this is only possible for version 0.9.1 and later.  For older versions of Stellarium you must edit the image).
 http://porpoisehead.net/misc/calc_landscape_rot1.png
@@ Line 12: / Line 14: @@
 where:
-*b is the bearing you want to have the chosen object, in degrees.  Use 0 for North, 90 for East etc.
+*'''b''' is the bearing you want to have the chosen object, in degrees.  Use 0 for North, 90 for East etc.
-*x is the distance in pixels from the left side of the image to the object you want to align.
+*'''x''' is the distance in pixels from the left side of the image to the object you want to align.
-*X is the horizontal image size.
+*'''X''' is the horizontal image size.
 For example, here's the landscape image again, with some measurements: