Reply With QuoteMay I ask why a 2:1 ratio map? Is that just a standard that is so common that any other ratio looks odd? I ask because I would love to do a 4:3 ratio due to the research I did for printers, and that does fit the shape of the continent very well.
Yes it is.Originally Posted by xtianstone
As I wrote this applies "For main sequence ". That means that this doesn't apply to giants and dwarfs.
But giants don't last long and white dwarfs (black dwarf don't exist yet in our universe because 14 billions years are too short to cool down a white dwarf) are remnants of a dead star so that normal stars spend most of their life on the main sequence where same mass implies same luminosity.
Now all this is perhaps relevant for your story but not really for your map.
May I ask why a 2:1 ratio map? Is that just a standard that is so common that any other ratio looks odd? I ask because I would love to do a 4:3 ratio due to the research I did for printers, and that does fit the shape of the continent very well.
It's one of those partial understanding things where knowing a little bit can actually be detrimental. There's a particular projection variously called "Plate Carree", "Equirectangular", or "Normal Tangent Equidistant Cylindrical", "Geographic", "Unprojected" (which is wrong), and a range of other things. It projects a sphere to a rectangle with an aspect ratio of 2:1. It's is a fairly simple projection to understand, draw a graticule (grid) for, or to plug into computations like computing distance or converting to other projections. On the other hand it's a horrible projection for displaying finished maps in most cases.
The reason it has a 2:1 ratio is simple. You can think of plate carree as measuring the distance to the equator along a meridian, then along the equator to the prime meridian, then replaying those two steps at right angles on a flat plane. The equator is twice as long as the meridians, so the map that results is twice as wide as it is high.
The projection is true at the equator, and distorts both area and angles as you approach the pole. Distances north-south are preserved, but all others are distorted, except at the equator. Drawing it without the correct distortion means you've distorted the features on the globe to compensate (pinching them toward the poles to compensate for the stretching of the projection).
All projections cause some form of distortion somewhere. Some can preserve angles, some can preserve areas, and some can preserve distances along lines through particular points. Some projections try to balance out the different kinds of distortion to provide a general overview. Some maps try to balance distortion over the globe while others focus on one area at the expense of the rest, and the smaller the area focused on, the less distortion there is within it.
This is why simply zooming in on a map and cropping the rest to make a map of a smaller region is usually a bad idea. It is also why different maps with different purposes have different projections. Navigational maps often use angle preserving projections while statistical maps often use area preserving ones.
This also means that things like graticules, scale indicators like scale bars, and bearing indicators like compass roses and rhumb lines can only be used on certain maps and in certain ways on those maps.
Modern cartographers generally avoid cylindrical projections for maps of the full globe unless there's a specific reason. Zoomable web maps generally use the cylindrical Mercator projection because it has technical advantages in that particular role. Hybrid projections like Winkel Tripel tend to dominate global reference maps while statistical maps are often done in equal area projections, particularly pseudocylindrical projections like Mollweide.
I would add to Hai Etlik the reason which is the most important for all people who are using the cylindrical projection.
It is the easiest one to understand and you can do nothing wrong when using it.
It is also one where you need absolutely no calculation to establish a one to one map between points on a sphere and points on a plane (only exceptions the 2 pole points).
You have the coordinates of a point on a sphere ? It's the same ones on the plane. You have the coordinates on the plane ? It's the same ones on a sphere.
This is why a map drawn in cylindrical projection can be transformed in a map on a sphere immediately even by hand without computing anything.
That's also why it is generally used only for maps that cover the whole world and not merely smaller parts of it where anything goes.
People doing amateur cartography mostly care about shapes and colors (coastlines, mountain range placement, rivers) and not about areas.
You draw a horizontal line at the upper edge of a map and you immediately get a circular polar cap on a sphere. So easy.
Of course there is a disadvantage that if you add a scale bar, it will be wrong on all places but not so much unless you get rather near to the poles.
I join an example of one of my maps which was first drawn in cylindrical (2x1) and then projected on a sphere.
Observe how shapes are conserved but the surfaces are much smaller near the poles even if the continets are still clearly recognised. Also note the perfect bijection between plane and sphere points.
Obviously as this projection conserves neither areas/distances nor angles it is very bad for Professional purposes (navigation, surface measures etc).
But we don't do navigation maps here.
Cylindrical projection.jpgSphere.jpg
There are other cylindrical projections besides equidistant. Notably Conformal Cylindrical (Mercator) and Equivalent Cylindrical (Including Gall-Peters and Hobo-Dyer).
It's also very possible to get things wrong when designing a world with plate carree. The most significant problem being "pinching" at the poles if you fail to draw things with a suitable level of east-west stretch.
Plate carree does not preserve shapes. Equidistant projections preserve distance toward-away from a point. Conformal projections preserve angles, which sort of preserves shapes. Exact shape preservation is not possible.
Polar ice caps aren't circular. Also, any normal aspect cylindrical or pseudocylindrical projection will give you straight, horizontal parallels, not just plate carree.
Shapes are most certainly not being preserved. You have significant pinching toward the poles. The orthographic projection you're using in the second image hides it a bit, but it's still clearly off. Looking at it close up shows just how much the shape is distorted. (using a stereographic projection centred on the landmass)
Untitled map.png
Thank you so much for the information and comments. I am going to work on my world map, but here are the projections for the continental sectional map.
I included a 2:1 and a 4:3. I would really like a 4:3 for the space I have chosen, but again I am expecting this to be a fluid morphing project!
Thoughts?
lineswide.jpg
lines.jpg
It doesn't appear to be a whole planet map so the aspect ratio is irrelevant. When you project the entire surface of a sphere (or spheroid) onto a plane, you get a particular shape, which may be infinite in some cases (some projections can't cover the entire entire sphere even taking infinity into account) Cylindrical projections give you a rectangular projection of the whole sphere and depending on the details of the projection (which one, what the standard parallel is) that rectangle will have a particular aspect ratio. Other projections can produce ellipses, circles, cardioids, fans, and all manner of other shapes. If you are looking at a restricted extent within that, the extent can be any shape. Practically speaking, you'll want the extent to line up with areas where the projection has minimized distortion, or more likely the other way around: given an area, you'll want to pick a projection that gives minimal distortion for it.
You seem to have slapped an arbitrary graticule (the grid) on top. From the look of it, you chopped it out of a Winkel Tripel or similar projection. That doesn't make sense for this map. If you want to do a world map in Winkel Tripel, you should use the entire Winkel Tripel graticule. If you want a regional map, then Winkel Tripel is a poor choice of projection.
the "habitable zone " ( or Goldilocks zone) depends on the star
as to IF a 0.9 to 1.4 Earth Mass planet is there and in a stable orbit
DOSE depend on IF there is one or two MASSIVE Jupiter size ones in the outskirts of that solar system
if a massive planet is NEAR the star
there will Be NO small planets in the area of liquid water
now the main problem with a STABLE!!!! orbit in a binary star system is well the stable orbit
they would happen but not often the two stars do need to be rather close and the planet orbit the common barycenter
something like a smallish red giant and a yellow dwarf would do
and both will need to be middle to OLDER age stars ( a new formed star will be WAY to active for any kind of life to have formed)
as to the map it's self
post #3 is a bit on the noisy side
and the idea of a full planet map is for YOUR reference and to make things easier for YOU
to add a bit on projection type
-- USE what you need to use -- simple
different formats are good for different things
( use the best tool for the job )
a wikipedia page
https://en.wikipedia.org/wiki/List_of_map_projections
also different software might work best with different formats
the 2:1 ratio and the other one the " power of 2 " size ( 1024x512,4096x2048 , 8192x4096) is for the 3d card you have in your computer
IF you use 3d software to render it
Last edited by johnvanvliet; 01-11-2015 at 09:16 PM.
--- 90 seconds to Midnight ---
--------
--- Penguin power!!! ---
Posting Permissions
