Sol 884 looks like a 39 meter move just to the left of the 15 meter circular black dune. I thought it was a crater.

A Navcam parallax measurment to the closest rim of Beagle is 75 -15/+22 meters ( 75 meters as measured on the map )

Hi Algorimancer.

Just wanted to thank you for your wonderful parallax tool AlgorimancerPG. I used it exclusively for the parallax measurments in my sol 883 position estimation.

I used the online tool MER Stereo Parallax Calculator for a long time, but discovered it was not very accurate for over 50 meters measurment. ( I routinely subtracted a 2 pixels correction. )

FYI, I remeasured several rocks after I refined the direction of motion and got a movement of 37.2 +/- 1 meters on a heading of 7.9 degrees right of center of the reference crater. Didn't make much difference in the original guess. The biggest error source is the center of the 10 meter reference crater.

I put Oppy about 7 meters south and 2 meters east of your position.

Measurments:

37 +/- 1 meters movement from measured parallax changes on a heading about 8 degrees to the right of the center of the crater just behind the 15 meter black dune crater ( BC) ;

49.5 +/- 1.2 to the front of the dune intersecting the crater on a line through BC;

Consistancy checks:

41.5 +/- 0.8 on a line 28.0 degrees from BC through Oppy position intersecting the left edge of the dune abutting the 15 meter black crater.

Also, visually, Oppy is now just in front of a fairly long stretch of outcrop -- the faint white line on the map.

Thanks Tesheiner for your dedication. Have a good vacation away from the Mars front.

James, thanks for picking up the cudgel and leading the charge. I will try to keep your back safe by continuing to hack my own route map and yelping when I think there is a difference more than a few meters.

I usually proceed by determining the direction of motion by comparing before / after panoramas.

pancam / pancam comparisons are the best, but pancam / navcam can work too.

I then determine the distance with a set of parallax computations of selected points in both before / after 3D pairs and then apply direction of motion cosine corrections.

I usually can determine the direction to a few tenth's of a degree and the distance to a few meters -- unless of course Oppy is in featurless dunes -- where the major difficulty is finding suitable features to parallax measure.

I agree with your 877 position -- but not the 876 position.

I measured a change in position of 24 meters +/- 1 meter, using a number of before / after move pancam points.

Curiously, where you place the "kink" agrees with my 876 position...

I always do my position calculations before I look at yours and it is reassuring when they are the same -- and distressing when they are not.

Now that we are again in a "feature rich" area, there should be no more differences.

Definitely looks better to me.

I measured the distance to the center of the dune crest down the center of the outcrop to be about 11 meters from Oppy and then drew a line parallel to the dune center 11 meters from the center.

I then measured 19 meters to the southernmost visible end of the outcrop -- and 33 meters to the edge of the small crater to the south. the arcs from these two points intersect the 11 meter dune line at about the same point -- about 5 meters to the south-west of your position.

Of course -- as always -- this assumes I am actually seeing corresponding points on the map.

Er, Tesheiner, did you check Ft Gibson size from the Navcam images yet?

My parallax measurments are:

to furtherest outcrop exposure north of Oppy is 32.4 m +/- 2.0;

to furtherest outcrop exposure south of Oppy 6.3 +/- 0.1 .

I chose to use the northern-most visible block as the start of the feature, reasoning that from orbit even a few patchy blocks will show up very bright.

so the outcrop is 38.7 +/- 2.1 meters long.

Looking at the feature I think the faint white area to the south of your sol 869 position is the southern end of the feature.

More troubling are the parallax measurments to the nearest outcrop from the current ( sol 875 ) position:

I measure 14.5 +/- 0.1 meters to the nearest outcrop and 25.8 +/- 0.3 to the other side -- for a width of 11.3 meters. There is a fairly large dune ripple down the center.

I think that Oppy is about 13 meters further south and a few meters west from your current position.

Er, I measure 50 meters movement for sol 869. The "fort" I think is the small outcrop spot about 13 meters further south.

Not so fast.

Notice the two lines that converge on the very weak near rim feature pass through two very bright features on the far rim. How can you near rim guys be so sure that we are not seeing two distinct far rim features on sol 804 and 859? It is pretty clear to me that we are dealing with a complex of features on the far rim -- not one puny outcrop on the near rim.

If the beacon is near rim, where are the other much brighter near rim features?

I would not pop the champaign cork just yet.

I will believe that the beacon is on the near rim when Oppy parks in front of it and reads the plaque that states "Here stands the infamous Victoria beacon -- a warning to all travelers that things are not what they seem. ".

Perhaps JPL is saying that the Beacon feature is 500 meters beyond the far rim of Victoria! None of my maps show any details beyond 400 meters.

Perhaps JPL's little joke on UMSF?

Er, 198228896 timestamp is April 13, 2006.

OK, a few points...

First, the beacon feature is not a point -- it is a structure which changes appearance with changing geometry and light. I am sorry if I have misled anyone. When I use the expression "Victoria Beacon" I mean the extended feature -- not the brightest point for any given time or geometry. I think the shifting position of the brightest point has led to the confusion about its location.

Second, as Oppy gets closer to Vicky, the angular width of any feature on the line of travel will increase -- faster for those on the "near" rim than the far rim.

For example, imagine Oppy 100 meters from a 10 meter block on the near rim. The angular width of the block is 5.72 degrees. The same block on the far rim 800 meters away is only 0.72 degrees wide. So at some distance the position of the beacon will no longer be Victoria's secret. Everyone will say, "aha", chuckle a bit -- and think about something else.

Er, almost all of my original images are in PNG format. What browser are you using that does not support PNG format?

I think you are confusing the geometry of referenced in reply 274 and the simple angular size change measurment used in sol 848-855 -- which works best when the motion is more or less towards the target.

The geometry referenced in reply 274 requires two colinear points towards the target and some transverse movement. The size change method requires two points perpendicular to the motion towards the target

I think my point was that both methods favor a far position for the beacon feature -- although the margin error is as large as the results -- at this point.

Perhaps there should be a pool as to when the issue will be resolved by a definitive measurment.

Er, actually I made measurments a month ago that supported the far rim hypothesis.

You may see the details in reply 227, 237 and 254 of the Victoria or Bust topic on the other blog.

Er, I measured the width of a series of features around the beacon that increased from 77 to 81 pixels on 2x images.

To summarize, from sol 848 to 855 Opportunity moved 105 meters closer to Victoria. That means the distance to a near feature changed from 1035 to 930 meters and the distance to a far feature changed from 1735 to 1630 meters. These are changes in angular size of 11.3 % for near features and 6.4% for far features.

Thus a feature of, say, 100 pixels wide on sol 848 would have increased on sol 855 to 111 pixels on the near side, but only to 106 pixels on the far side.

The features I selected were from the far left of the "bright spot" to the far right of slightly bright spots just above the horizon. It is best to look at the stereo pair to make this judgement.

For me the best evidence was looking at the stereo pair after changing the size of the sol 855 image by 0.940% and 0.898% in Stereophoto Maker. The 0.898% change, corresponding to the beacon features on the far side, looked, um, subjectively better matched.

Of course, I could be just imagining I see matching features -- but I think the technique is valid.

Comparison of Beacon feature on sol 848 and 855:



If the beacon is a near rim feature, then it should have increased in size about 11% between sol 848 and 855.

If it is a far rim feature, then it should have increased about 6% in size between sol 848 and 855.

I measure an increase in about 5%.

Ergo, it is on the far rim.

I welcome other measurments, but, in any event, in the coming sols the issue should be settled without question by the change in feature size.

You know Zeke4ther, there is no excuse for you not to have visited The Other forum.

I can understand not participating, but not even to kick the tires and take a test spin?

So... what will it take to get you into a used, low milage Mondeo -- hardly ever on the road except for occasional trips between Mars and Reading with the wife and kids to pay on the £127,000 mortgage?

If you are simply interested in some more color by Horticolor, you can try here.

You might be interested to know that I had just completed my sol 850 route map when you posted yours -- and your map and mine was within a pixel of one another!

Corner crater was 4.64 degrees wide -- which put it at 432 meters distance and the distance moved since last sol was 36 meters ( pancam / navcam parallax measurments ) and the distance to the next major outcrop along the dune trough was 107 meters ( pancam parallax ) and the angular separation between corner crater right edge and a really neat 5 meter tilted crater at 85 meters +/- 15 ( navcam parallax) was 112 degrees...

I don't think I will bother doing an independent map anymore.

This would make an interesting special effects image.

All you need to do is add some shadows, tracks. better size, lighting and perspective match for the rover...

Doesn't look like Michael is monitoring this thread anymore.

I tried antivig 2.0.2 -- worked great!

Here is my first antivig panorama:



tried the new version -- looks like some interesting features -- but the saves -- don't.

Anyway, I will use the tool for future pans -- including the McMurdo pan...

Thanks Michael -- wherever you are.

Hi Michael,

I have been interested in your anti-vignetting program for some time -- but have resisted the HUGE ( 118 MB ) download of IDL6.3 VM.

Well, I just downloaded the VM and your new version -- but before I run the VM install I want to understand the implications.

How does the IDL VM interact with the O/S -- specifically Windows 2000?

Requirements? I am running a Pentium 4 @ 1.5 GHz with 768 MB of memory. I am a little short of disk space on C ( down to my last few GB ) but have about a 100GB free on D.

Looking forward to producing some "professional looking" panoramas utilizing your tool.

color by horticolor: more real than real.

Latest McMurdo panorma here.

I will continue to update this page as additional filters are available.

In recognition of things Danish, perhaps these lines from The Tragedy of Hamlet, Prince of Denmark summarize my view on the near / far beacon debate:

Look here, upon this picture, and on this,
The counterfeit presentment of two brothers.
See, what a grace was seated on this brow;
Hyperion's curls; the front of Jove himself;
An eye like Mars, to threaten and command;
A station like the herald Mercury
New-lighted on a heaven-kissing hill;
A combination and a form indeed,
Where every god did seem to set his seal,
To give the world assurance of a man:

In other words -- far rim.

Er, thanks mhoward.

I think autostitch must weight each join match equally -- so the near point errors introduced by non-panoramic images cause uncorrectable distortions in the panorama. A better scheme would be to weight points near the top of the panorama more heavily. Perhaps a user option parameter? 100 to -100? ( top to bottom weighting ?)

I think that I will end up using PT Assembler for the "final" product.

For those not aware, the rover camera images are NOT proper panorama images: The cameras do not pivot through the optical axis of the camera.

For people interested in real panoramas with a lot of depth this is an important factor.

Also also a uniform exposure and white balance is critical to a totally successful panorama. Again lacking in the rover images.

But we do what we gott'a do and work with what we have.

We go to the computer with the images we have and not the images we would like.