Search found 179 matches

by quadibloc
Thu Apr 23, 2020 11:32 pm
Forum: Map projections
Topic: Experimental projections
Replies: 30
Views: 1229

Re: Experimental projections

Hufnagel and HEALPix are modern projections that relax the requirement of monotonically decreasing parallel length. Denoyer relaxes the constraint of constant scale along parallels. Relaxing that latter constraint is not a definition I would use, ever. I agree about the Denoyer projection not being...
by quadibloc
Wed Apr 22, 2020 10:55 pm
Forum: Map projections
Topic: Experimental projections
Replies: 30
Views: 1229

Re: Experimental projections

I mean the tristandard projection has no scale distortion either on the standard parallels. I'll have to admit that I missed that important point. I could say that Daniel Strebe's example, using the Hufnagel projection, does have yours beat. But I think that it's funny-looking too. At least it's ob...
by quadibloc
Wed Apr 22, 2020 4:34 pm
Forum: Map projections
Topic: Experimental projections
Replies: 30
Views: 1229

Re: Experimental projections

Of course it looks funny, but as it's just presented as an experimental projection, that's not really a valid criticism. However, it doesn't seem to be equal-area. With that constraint removed, it's trivially easy to do so much better: http://www.quadibloc.com/maps/images/merla.gif No shearing disto...
by quadibloc
Tue Apr 21, 2020 1:51 pm
Forum: Map projections
Topic: On distortion and optimal projections
Replies: 94
Views: 3410

Re: On distortion and optimal projections

Not that I know of. It’s unlikely that such a projection would have a general solution that can be expressed in known functions. I certainly haven't heard of it. But I can imagine what such a projection might be like for three values of the parameter: 0: the Stereographic of the whole world 0.5: th...
by quadibloc
Mon Apr 20, 2020 3:03 pm
Forum: Map projections
Topic: Gilbert two-world perspective doesn't make sense
Replies: 27
Views: 296

Re: Gilbert two-world perspective doesn't make sense

The North Pole is indeed "in" the Gilbert two-world perspective projection, and regions very close to it do appear twice on the map. That's because the projection, in its normal aspect, shows a globe tilted slightly forwards, so that its North Pole is visible. This isn't just due to the aspect of th...
by quadibloc
Mon Apr 20, 2020 9:09 am
Forum: Map projections
Topic: Experimental projections
Replies: 30
Views: 1229

Re: Experimental projections

Luca_bat_map wrote:
Thu Jan 10, 2019 10:30 am
Talking about experiments... what do you think about this one?
I like it a great deal, but of course I could be biased.
by quadibloc
Thu Apr 16, 2020 12:55 am
Forum: Problems with Geocart 3
Topic: Do Van Der Grinten I and Van Der Grinten II uh... not have the middle Indicatrix?
Replies: 22
Views: 231

Re: Do Van Der Grinten I and Van Der Grinten II uh... not have the middle Indicatrix?

In the large-scale projections world, you have to be specific about which series development or approximation you use. Any official system is specific about that, often even down to how many digits to round to at what steps. Oh, indeed. And, of course, in the world of large-scale projections, one h...
by quadibloc
Wed Apr 15, 2020 5:04 pm
Forum: Problems with Geocart 3
Topic: Do Van Der Grinten I and Van Der Grinten II uh... not have the middle Indicatrix?
Replies: 22
Views: 231

Re: Do Van Der Grinten I and Van Der Grinten II uh... not have the middle Indicatrix?

Van der Grinten’s patent filing was for a drafting method. There are no “official” formalæ. I realize that you're responding directly to the specific phrasing used. But still, that sounds strange to me. After all, a "drafting method" directly implies the (forwards only) formula to which it is equiv...
by quadibloc
Mon Apr 13, 2020 12:49 pm
Forum: Problems with Geocart 3
Topic: Do Van Der Grinten I and Van Der Grinten II uh... not have the middle Indicatrix?
Replies: 22
Views: 231

Re: Do Van Der Grinten I and Van Der Grinten II uh... not have the middle Indicatrix?

These two projections are extremely troublesome around the origin. 25 years ago, when I implemented them, I spent a lot of time trying to work out a series development for longitude close to the prime meridian and latitude close to 0 within that. I only managed a partial solution. I can sympathize....
by quadibloc
Sun Apr 12, 2020 5:17 pm
Forum: Mapmaking
Topic: Globemaking (simple shapes)
Replies: 9
Views: 475

Re: Globemaking (simple shapes)

daan wrote:
Tue Apr 25, 2017 10:55 am
Is there a Web page that shows or describes the Kinder Surprise artifact? I didn't find anything obvious.
Because of a percieved choking hazard, Kinder Surprise eggs may not be legally imported in the U.S. from Canada. That may be why they are unknown to you.