High Resolution Texture Of Venus

[ANDREA]

EXCELLENT, Andrea! I would be quite interested to have a look at the 4k.dds. Did you correct already for Celestia's center Meridian position which is usually different by 180 degrees from Steve's.
Bye Fridger

Thank you Fridger, appreciated.
I have rotated 180 degrees and modified the map as for the central meridien, I think this is what you was asking for, correct?
This is a 0.8k jpg

Moreover I have darkened (lower gamma) the image, hope this will be OK for Malenfant too.
Naturally if someone likes it I have the 4k.DDS file, 10.8 MB.
Bye

Andrea

[Malenfant]

I have rotated 180 degrees and modified the map as for the central meridien, I think this is what you was asking for, correct?

No, you've turned the map upside-down!

I think what Fridger meant is that you shift it 180 degrees in LONGITUDE. In other words, if the middle of the map is the 180 degrees longitude line, then you need to cut the map exactly in half down the middle, slide one half over to the right, and the other half over to the left so that the 180 longitude line is on the left/right edges of the map and the 0 longitude line runs down the middle.

[danielj]

I didn??t know that the 16kNewVenus.dds is STILL a crude texture.I thought it was nearly complete,considering the long time it is available.Actually,I still didn??t finish downloading the 8k Vensu texture and 8k Venus NormalMap and don??t know if I would have any problem.I will tell so.
But It??s a pity that no one is working in a 16k good map of Venus or even a 32 k map of Mars...

Nope.I downloaded it and it was in black and white.I downloaded form index of creators:
http://celestiamotherlode.net/creators/johnvanvliet/
I downloaded the 16kNewVenus.zip file.

I downloaded today all three textures from the same page, and 4k and 8k are in color, and both cleaned by John, as you can see here
4K

8K


The 16kNewVenus.zip file is in B&W (but I had no problem to open it), but it's a crude texture, with all the artifacts, missing parts, errors and so on.
If you cannot see the 4k and/or 8k in color, sorry for you, Danielj, but surely you have some problem in your PC, or PhotoShop, or something else.
I suggest you to check if in the Photoshop settings there is something that doesn't allow .png file in color, or if you have "Image" "Mode" "Grayscale" enabled.
Good luck.

Andrea

[ANDREA]

No, you've turned the map upside-down! I think what Fridger meant is that you shift it 180 degrees in LONGITUDE.

Sorry Malenfant, but I don't agree.
If you look my previous images and the last one, you'll see that the image is rotated 180 degrees, and NOT upside-down, and that moreover the central meridian has been modified.
Here I show them again close each other, with as comparison a 0.8k jpg copy of Praesepe's 2k image, perfectly close to mine (as are the 4k and 8k by JohnVanVillet):




Please inform me if I'm making some mistake, or if all Praesepe's, JohnVanVillet's and mine Venus images are wrong in alignment/rotation.
Bye

Andrea

[Malenfant]

Well, Fridger was definitely talking about making sure that the central meridian was in the right place. It may be that you'd already done that, in which case ignore me .

Though now you've got me wondering. In Celestia, should Maxwell Montes (the very bright patch left of the top-centre of the image below) actually be near the top of the texture or near the bottom?



Usually this image is how I've seen maps of Venus displayed. Maxwell Montes is near the north pole of Venus (see http://planetarynames.wr.usgs.gov/altimetry.html for example - Maxwell is on the North Pole (Ishtar Terra) map, and its location is stated as 65N 3W - see this map and this page). So usually, Venus textures and maps are displayed with the north pole at the top of the image.

What I'm not sure about now I think about it is whether Maxwell is near the north geographic pole (ie the axis at right angles to the eliptic, pointing in the same general direction as Earth's axis and most of the other planets except Uranus and Pluto) or if it's near the north rotational pole (eemember Venus has a tilt of 178 degrees, so it's rotating nearly 'upsidedown' relative to Earth and most of the other planets).

So if Maxwell is near the north geographic pole of Venus then you're right - the texture should be 'upside-down' compared to the image I've shown here. Then Celestia will use the obliquity of Venus to rotate the texture 178 degrees so that it appears to be in the northern hemisphere as seen from Earth. And when I look at Venus in Celestia, Maxwell is in the northern hemisphere as seen from Earth and the texture is "upside down" to how it's usually shown.

I think what is confusing me is that the NASA sites give the co-ordinates in a way that implies that North is in the opposite direction to the orientation of the axis around which Venus rotates (i.e. in the same frame as Earth's).That seems counter-intuitive to me - on Earth, the north rotational pole is 23 degrees off the north geographic pole. So you'd think that if Earth had Venus' tilt then (for example) Greenland would still be described as having coordinates of 72N 40W even though it'd be actually in the southern geographic hemisphere.

[John Van Vliet]

hi it's john some how i managed to deleat my big venus vert tex( 32k) and all the orig. maps when i converted to linux ( i thought i had them on cd )
so i am starting over with 100px/deg. maps from pds map a planet

and the missing data will be inpainted and the image smouthed out and sharpend

[scalbers]

My software is written pretty much from scratch in IDL, so I'd have to learn a little bit more about standard soft masking techniques and the best way to code them. Any quick online references to them that you are aware of?

Perhaps I'm trying to straddle the line between the planetary science and the more artistic community - I may run the risk of pleasing neither as a result ??

I think the obvious solution is to have two textures - one that is realistic and reflects the limit of knowledge (complete with image artifacts), and one that is "pretty", that hides the artifacts but creates fictional data in the process (even if it's just making different resolutions look like they're the same, or sharpening images).

You using ISIS, BTW?

Great discussion and imagery illustrating the possible compromises. Fortunately there is lower resolution data to fill in most of the Magellan gaps. Some type of artificial sharpening would be an option as you suggest.

I'm unsure if ISIS can be easily installed on my SuSe LINUX machine. I am using IDL with remapping code written mostly from scratch.

The Venus data in my view has to be handled differently from other objects I've worked on in terms of soft masking strategy. The gaps in the Magellan data are generally either very small or very narrow, so there isn't much "room" to spread out a soft masking effect. As a first experiment, I will try adjusting the Magellan data as a smooth function of longitude to help ensure a better local brightness fit when it is added as an overlay to the lower resolution map I'm using from Calvin Hamilton.

[Malenfant]

I'm unsure if ISIS can be easily installed on my SuSe LINUX machine. I am using IDL with remapping code written mostly from scratch.

I dunno about "easily" but I'm sure it can be installed. I think you need a few old libraries for it to run though.