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[Complete] Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Printable Version

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Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Jaco van der Molen - 2020-07-25

Hi all,

Is this part done?


Can the globe print be done trough texture mapping?
The part exists.

I am trying to make the image for mapping, but I am unsure how to map the image on the part.

Something like this (WIP)
   


[Image: 61287pb002.jpg]
[size=xx-small][font=Tahoma,Arial]* 

 2 
 61287pb002
Dark Tan Cylinder Hemisphere 2 x 2 with Cutout with Europe, Africa, Asia, Australia Reddish Brown Globe Pattern
CatalogPartsCylinder, Decorated

[Image: dot.gif]
[Image: 61287pb001.jpg]

 2 
 61287pb001
Dark Tan Cylinder Hemisphere 2 x 2 with Cutout with the Americas and South Pacific Reddish Brown Globe Pattern
CatalogPartsCylinder, Decorated[/font][/size]


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Orion Pobursky - 2020-07-25

This is one of the outstanding patterns for the modulars. If you come up with a good image, it can prolly be TEXMAPed.


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Travis Cobbs - 2020-07-26

(2020-07-25, 14:15)Jaco van der Molen Wrote: Can the globe print be done trough texture mapping?
The part exists.

I am trying to make the image for mapping, but I am unsure how to map the image on the part.

It should be straightforward using spherical mapping. The attached file will map earth.png (not included) onto a sphere. (That just needs to be any map of the Earth using Mercator Projection, I think.) Obviously, mapping it onto the part is a bit more difficult, but it shouldn't be too hard.


.ldr   earth.ldr (Size: 493 bytes / Downloads: 5)

Note that the LDView 4.3 doesn't support spherical mapping, although LDView 4.4 will. LDD already supports it, as far as I know.


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Jaco van der Molen - 2020-07-26

(2020-07-25, 16:10)Orion Pobursky Wrote: This is one of the outstanding patterns for the modulars. If you come up with a good image, it can prolly be TEXMAPed.

OK, I am guessing the image should be square?
I do not have the part (yet), but can we do some testing with an image?
If you can provide the code for the part, I can make the image.

I have been studying the spherical texture mapping but had no success to make it work :-(


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - N. W. Perry - 2020-07-26

(2020-07-26, 1:48)Travis Cobbs Wrote: It should be straightforward using spherical mapping. The attached file will map earth.png (not included) onto a sphere. (That just needs to be any map of the Earth using Mercator Projection, I think.)

Not just any map, but one where California is mythologically depicted as an island.  Wink


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Magnus Forsberg - 2020-07-26

I have no idea of what I'm doing but this works, sort of.
I used, and adapted the example from Travis below.

   

Something breaks around the northpole.


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Magnus Forsberg - 2020-07-26

(2020-07-26, 16:09)Magnus Forsberg Wrote: I have no idea of what I'm doing but this works, sort of.
I used, and adapted the example from Travis below.



Something breaks around the northpole.

Would it render better if the surface was recreated using a sphe primitive?
What does the difference between concave and convex triangles mean for the final impression?
Why are the lines wobbling?


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Travis Cobbs - 2020-07-26

(2020-07-26, 16:09)Magnus Forsberg Wrote: I have no idea of what I'm doing but this works, sort of.
I used, and adapted the example from Travis below.



Something breaks around the northpole.

One problem with spherical mapping is that things go bad at the north and south poles. This isn't a problem on the bottom due to the fact that there's nothing at the south pole, but two polygons on top share the north pole as one of their vertices.

Another problem is that your image needs to be quite a bit taller than it currently is to work as a mercator projection. It seems like the image you have is roughly -80 to +80 latitude. If you change the the second 180 to 160 in the !TEXMAP line to reflect this, things get a bit better, but still not perfect (at least in LDView). I need to check to see if there is a bug in LDView. The top edge of the texture doesn't work well. Having said that, there is no way to apply two separate textures to the same geometry, so having a texture stop in the middle of a polygon leaves the rest of that polygon blank, and there's nothing you can do about that.

If the sphere geometry stopped at +80 degrees, and then a cone was used above that, a separate texture could be applied to the cone from above, and things would probably look pretty good. (Getting that texture to line up would take some work, but it would certainly be possible.) In that case, your existing texture would work great with a 160 degree vertical span.

I also tested by resizing your original image to be 1600 pixels tall, and just filling in the new space with the tan background (leaving the angle in the file set to 180). That actually improves things a lot, but the longitude lines then stop before the pole, and extending them up runs into the north pole discontinuity problem again.

As for the wiggly lines, I think that is caused by the fact that the spherical geometry is so low-resolution.


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Jaco van der Molen - 2020-07-27

(2020-07-26, 21:52)Travis Cobbs Wrote: One problem with spherical mapping is that things go bad at the north and south poles. This isn't a problem on the bottom due to the fact that there's nothing at the south pole, but two polygons on top share the north pole as one of their vertices.

Another problem is that your image needs to be quite a bit taller than it currently is to work as a mercator projection. It seems like the image you have is roughly -80 to +80 latitude. If you change the the second 180 to 160 in the !TEXMAP line to reflect this, things get a bit better, but still not perfect (at least in LDView). I need to check to see if there is a bug in LDView. The top edge of the texture doesn't work well. Having said that, there is no way to apply two separate textures to the same geometry, so having a texture stop in the middle of a polygon leaves the rest of that polygon blank, and there's nothing you can do about that.

If the sphere geometry stopped at +80 degrees, and then a cone was used above that, a separate texture could be applied to the cone from above, and things would probably look pretty good. (Getting that texture to line up would take some work, but it would certainly be possible.) In that case, your existing texture would work great with a 160 degree vertical span.

I also tested by resizing your original image to be 1600 pixels tall, and just filling in the new space with the tan background (leaving the angle in the file set to 180). That actually improves things a lot, but the longitude lines then stop before the pole, and extending them up runs into the north pole discontinuity problem again.

As for the wiggly lines, I think that is caused by the fact that the spherical geometry is so low-resolution.

OK, I will do some testing with the image and test the part Magnus made.
If all goes well I will have the physical part tomorrow so I can try match the worldmap as good as possible.


RE: Cylinder Hemisphere 61287pb002 and 61287pb001 (Earth map / Globe) - Magnus Forsberg - 2020-07-28

(2020-07-27, 20:39)Jaco van der Molen Wrote: OK, I will do some testing with the image and test the part Magnus made.
If all goes well I will have the physical part tomorrow so I can try match the worldmap as good as possible.

Please note that I repositioned the subfiles to fit the image, instead of moving the image.
This part, 61287, have a bad orientation. The outside, printed surface, will end up on the backside, in default position.

I have some ideas on how to change the surface. Let me know if you need help with the shape of the part.