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Venera Images, VENERA 13 fully calibrated image
mcaplinger
post Sep 12 2006, 04:40 AM
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QUOTE (DonPMitchell @ Sep 11 2006, 06:28 PM) *
I added a little extra info about the project on my blog: Venus in Perspective

Very interesting and well-done. One question: the "channel" in the mid-field of the image on your blog page seems suspiciously aligned with the edges of the image coverage. Is there really reason to think this is anything but an artifact of your processing? I wouldn't want people doing photogeology on the basis of seeing this feature if there isn't real evidence for it.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Guest_DonPMitchell_*
post Sep 12 2006, 06:26 AM
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QUOTE (mcaplinger @ Sep 11 2006, 09:40 PM) *
Very interesting and well-done. One question: the "channel" in the mid-field of the image on your blog page seems suspiciously aligned with the edges of the image coverage. Is there really reason to think this is anything but an artifact of your processing? I wouldn't want people doing photogeology on the basis of seeing this feature if there isn't real evidence for it.


The persective images are derived from superimposing different projections, with photoshop. I explain that on my latest blog entry. Geologists would not use an image like that to do any kind of analysis. They are just meant to convey the big picture of what the terrain looks like, in a familiar camera perspective. For photo interpretation of geology, you would look at the new unprojected images, with the improved radiometric response function, or even the individual perspective projections, like the three partitial images I show.

Soviet researches, at one time, reprojected the Venera images into the cylindrical form returned by the Viking Mars lander, to help make comparisons in a projection that planetary geologists had become use to studying.
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AndyG
post Sep 12 2006, 08:40 AM
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Well done, Don.

You've managed to make me beat my shortest-lived wallpaper ever record, when yesterday's stunning LPOD Plato shot was bumped off my monitors this morning to be replaced with your Venusian Hills.

Beautiful imagery - I have to agree with David with regards to making Venus a place, with work as good as this.

Andy
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dilo
post Sep 12 2006, 11:01 AM
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Don, my first attempt to produce vertical/polar projections showed unacceptable distorsion in the lower part, due to the fact that your image isn't an equirectangular projection but is probably closer to a wide-angle image with rectilinear correction (like some processed hazard cam images from MER).
After applying to the original some "pincushion" distorsion and assuming 90 deg FOV, results appear better (vertical projections for V13 and 14 respectively):
Attached Image
Attached Image

Do not know real scale (should be a 0.5cm/pixel assuming a camera height of 1m); someone can calculate based on the probe features...
Here the corresponding pseudo-polars:
Attached Image
Attached Image


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Guest_DonPMitchell_*
post Sep 12 2006, 11:42 AM
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The images were originally 800 x 600, and the sky was later extended by 200 pixels. So the camera is perspective projection, but it is pointing downward a little. Just delete the upper 200 pixels and try. Here is the code that made the image:

CODE
//
//  Take a picture with a perspective camera
//
#define NWIDE 800
#define NHIGH 600

static void
Camera(double fTheta, double fPhi, char *sz)
{
    ML_Vector3 v;
    double x, y, z;
    ML_Image im;
    ML_Matrix3x3 matTilt;
    int i, j;

    im.NewImage(NWIDE, NHIGH, 1);
    matTilt = ML_EulerMatrix(fPhi*D_DTR, 0.0, fTheta*D_DTR, "xyz");
    y = 0.45 * double(NWIDE);
    for (i = 0; i < NWIDE; i++) {
        x = double(i - NWIDE/2) + 0.5;
        for (j = 0; j < NHIGH; j++) {
            z = -double(j - NHIGH/2) - 0.5;
            v = ML_Vector3(x, y, z);
            v = matTilt * v;
            v = s_matCamera * v;
            im.Set(SampleVector(v), i, j);
        }
    }
    im.WriteBMP(sz);
}
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mars loon
post Sep 12 2006, 12:15 PM
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Don,

beautiful work. fantastic hills. I will now plan to show them at our astronomy club meeting in Princeton tonight as part of a review of recent discoveries and the Viking 30th anniversary

ken

http://www.princetonastronomy.org/
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mcaplinger
post Sep 12 2006, 01:57 PM
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QUOTE (DonPMitchell @ Sep 11 2006, 11:26 PM) *
Geologists would not use an image like that to do any kind of analysis.

You haven't worked with a lot of geologists, have you? smile.gif


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Guest_DonPMitchell_*
post Sep 12 2006, 03:56 PM
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QUOTE (mcaplinger @ Sep 12 2006, 06:57 AM) *
You haven't worked with a lot of geologists, have you? smile.gif


Hehe. Well I can say that Alexander Bazilevsky or Jim Head would know better. I could put some sort of "cape does not allow wearer to fly" warning on my picture, I suppose. :-)
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Guest_Myran_*
post Sep 12 2006, 05:36 PM
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You're in the news mr DonPMitchell. biggrin.gif
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t_oner
post Sep 12 2006, 06:21 PM
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A quicktime VR would be nice.
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Guest_DonPMitchell_*
post Sep 13 2006, 02:53 AM
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QUOTE (Tayfun Íner @ Sep 12 2006, 11:21 AM) *
A quicktime VR would be nice.


That's an interesting idea. I'll have to look into how to generate an image for QVR. I've used it (and its inventors are friends of mine, in fact), but I've never tried to generate content for it. Does the standard Quicktime plug-in everyone has show QVR images?
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JRehling
post Sep 13 2006, 02:57 AM
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QUOTE (Tayfun Íner @ Sep 12 2006, 11:21 AM) *
A quicktime VR would be nice.



Venusian Reality?
laugh.gif

Might be fun except for the screaming and combusting.

ohmy.gif
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Guest_DonPMitchell_*
post Sep 13 2006, 03:45 AM
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QUOTE (JRehling @ Sep 12 2006, 07:57 PM) *
Might be fun except for the screaming and combusting.


The temperature on Venus is approximately the same as an oven in self-cleaning mode. But the dense high-pressure CO2 atmosphere would greatly increase heat conduction, and super-critical CO2 behaves like a non-polar solvent. It's not a highly oxydizing atmosphere, so there would not be flaming combustion. Someone stepping out in shirt sleeves would be french-fried in mid air and eventually reduced to a char coal figure.

So, important safety tip.
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lyford
post Sep 13 2006, 06:34 AM
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QUOTE (DonPMitchell @ Sep 12 2006, 07:53 PM) *
Does the standard Quicktime plug-in everyone has show QVR images?

Yes, it should.


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"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
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AndyG
post Sep 13 2006, 09:43 AM
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QUOTE (JRehling @ Sep 13 2006, 03:57 AM) *
Venusian Reality?
laugh.gif

Might be fun except for the screaming and combusting.

ohmy.gif

The moment 90 atmospheres of furnace-hot CO2 starts to pour down your throat, I would imagine that screaming's not really going to happen. ohmy.gif biggrin.gif

But it's interesting that the view now feels so "normal". It could almost be an Icelandic image, or perhaps the top of a Scottish munro on an overcast day - walk over there and look down into a lochan. Maybe surprise a grouse behind that rock - the real Venusian environment doesn't seem to come across in this picture much if at all, whereas, in the originally portrayed slices, there was somehow a sense of a truly alien and hellish world, snapped in a few precious minutes between landing and melting.

For me, that makes it such a remarkable picture. Don's created our sister planet from scraps, and given us a familiarity that I certainly haven't had before. And I suppose that means we can now wonder - especially on the back of the MERs - about exploration. What lies over that edge, what vistas would greet us?

Andy
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