I made a similar mosaic, but shifted on the left by 1 frame (more Erebus inside): a 3x exhageration and unstretched anaglyph... I would like to see Oppy at the base of the dark wall (near the image center) in the next days

The Payson outcrop would seem to be a bit more difficult to get to with more sand along the path. We will have clearer views of that route once Oppy gets to the Mogollon outcrop. In the meantime, if there is an IDD problem, I'd expect that Oppy will stay at the present bedrock area while evaluating the problem. Otherwise, we are within a couple of Sols of Mogollon.

--Bill

Now, that's interesting! Good catch, Bill. I should have expected something like that, but I wasn't even looking for it.

It isn't something I'm making a conscious effort to look for; but when I see a lineation like this I habitually scan either side for matching patterns and this one was obvious.

--Bill

Part of a great sunset sequence:

Colour

Good catch Sunspot!

Here is an animated GIF with the 8 L2 pancam shots.
It starts at 17:31:53 and ends at 17:58:12.

Click to view attachment (673k)

A beautiful complement to one from early in the mission

Bookmark sol 657.
A 7x3 pancam mosaic in L257 (some 90ºx45º fov).
---
657 p2281.03 12 0 0 12 6 30 pancam_erebus_col_1_L257R1
657 p2282.03 24 0 0 24 4 52 pancam_erebus_col_2_3_L257R1
657 p2283.03 12 0 0 12 4 28 pancam_erebus_col_4_L257R1
657 p2284.03 24 0 0 24 4 52 pancam_erebus_col_5_6_L257R1
657 p2285.03 12 0 0 12 4 28 pancam_erebus_col_7_L257R1

Mogollon Rim: so close.... but can Oppy get there?
http://qt.exploratorium.edu/mars/opportuni...KCP2282L7M1.JPG

I seem yes.
Click to view attachment

It is possible to approach to rim to analyze the black stones which draw me lots of attention. This rim looks like that there are stratified sediments on the upper side and the lower side there are eroded and fallen stones from there.

Rodolfo

What is the maximum height of Mogollon Rim?

I took the picture http://qt.exploratorium.edu/mars/opportuni...KCP2282L7M1.JPG
to measure.

According to GIMP graphic tool : From the Oppy position to Mogollon rim is aprox 790-795 pixels and the heigth of rim: from bottom to the line between dark and white line is 40 pixels and the top of the rim is around 60 pixels from the bottom. At that moment, I am not able to get information about the conversion of length by pixels. Someone might jump it.

Rodolfo

What we usually see under the top layer of soil in Meridiani is darker material, so maybe some of the dark regions at Mogollon Rim are just places where large scale (and relatively recent ?) surface subsidence has taken place.

I'm looking at this and what I see is a flat, raised plateau of the same type of pale rocks the Erebus highway had, then the dark rocks are the underside or a substrata of the plateau. It seems in places that the dark areas undercut the white top. In the center of the picture, you can see paler rocks that have fallen off the plateau top. The dark color could be attributed to the perpetual shade. Perhaps too, aeolian forces have been able to erode the bottom layers more easily than the top.
And perhaps I am imagining all this because of my cold medecine.

Remember where we are: there is a 300 meter excavation next to us.

--Bill

First of all you must determine the distance to the feature, either by parallax or using a traverse map (ours, official). Oppy's sol 651 position in the official map on the MER webpage is accurate enough, and gives about 93m to the dark outcrop's center.

Second, you must convert the feature height in the image from pixels to angular size. Pancam pics have 16.8º fov, so given a height of 60 pixels (that is what I get from your post) it corresponds to aprox. 0.984º.

Third and last, you can approximate the feature height (in meters) by:
h = d * tan (a) = 93m * tan (0.984) = 1.6m

Somehow I was imagining that they would have Opportunity go around the outside, and avoid driving on the soft sand, but it is worth trying to take the route you've given here. We'll need to do something similar as we climb the rim of Victoria.

I still do not think there is a dark unit at all. This appears to me to be just shadow from an overhang or near overhang. I would suspect however that the lower more eroded layers are of a softer material.

Scott

Here is a 21 image panorama around Erebus.

Taken with the L7 pancam on Sol 657.

jvandriel.

Tesheiner: Very glad to hear from you and it is an excelent ones. However, I need to overcome one thing to understand it and be able to measure any position in the future.

One thing I still don't able to figure out is about the Pancam pics have 16.8º fov.

According to MARS Stereo Parallax Calculator:
Camera: PANCAM
nleft: 512 pixels
nright: 500 pixels
dim: 790 pixels

object distance: 7.54 m, one-pixel error: 0.027 m
object dimension: 166.9 cm

You mean that this is as the view angle of Pancam. I think I need one more detail to understand it. Let suppose that 16.8º takes how many pixels?

How do you convert from 60 pixels to 0.984º?

I have engineering background so I can recall it easily after using an calculator....

Rodolfo

Here is an anaglyph view of the area from MMB. I hope we go check out the dark laying on the sand on the right. I call it the Opportunity's "Turkey" since we first saw it around Thanksgiving, and it looks a bit like something that was left in the over rather too long.

Indeed the traced route is transversable:

1) Gentle slope, less than 5 degree. This is the most important factor.
2) Bottom of ripples (middle of ripples) which are harder and it is the most compact sand.
3) Word of caution specially at close of rim which I don't see very well and when Oppy is around 80 meters, must evaluate again the surface.

Rodolfo

I think he meant 0.984 minutes of arc not degrees.
16.8*60/1024=0.984375

Good!

Now it is even narrower to understand it.

My previous append asked about what is the meaning of 16.8º minutes of arc. Is that the wide view of Pancam from the bottom of surface of the border of rim up to the top of rim?

Then, the next question is how this minutes arc, 16.8º is obtained? Is that fixed number since the Pancam heigth is constant?

Thanks

Rodolfo

That's the effective Field of View (FOV) of the PanCam - and since it is a square 1024x1024 sensor it doesn't matter if your are talking about the horizontal or vertical aspect.

It's a fixed number because the Pancam has a fixed focal length, the FOV has nothing to do with the Pancam's height. The height of the PanCam becomes very relevant when you are trying to figure out the exact location of or distance to something in one of its images based on the parallex from Left Right image pairs.

Tesheiner and Helvick
Closed. Thank you much.

[nostalgia mode]
We're within a week or so of the one Earth year anniversary of Oppy leaving Endurance Crater, aren't we? I can't remember or find the exact date but I believe it was in the first or second week of December 2004. Despite the spectacular views of Burns Cliff, remember how eager many of us were to get her out of that crater and have her exploring new ground?

Do you think we'll be at the edge of or inside Victoria Crater at this time next year? I don't think Erebus will be quite as fondly remembered as was Endurance.
[/nostalgia mode]

She exited on sol 315, December 12 2004. Definitely some amazing progress made since then.

Maybe new images aren't very intriguing from this point, but there are some cool PanCam mosaics from Sol657 (Erebus rim, 3x stretch) and stratified outcrops from next Sol (50% of original scale)...
Click to view attachment Click to view attachment
Oppy PanCam is taking also a SuperRes sequence toward this dark patch:
Click to view attachment
Do someone can/want combine all 17 images from this sequence?

Stacked using Registax; then cropped and gamma enhanced.

Still looks like a rubble pile of dark rock

Airbag

I don't know where the 16.8 degree FOV figure originally came from, (it's mentioned on various sites on the net) but it is wrong! The Pancam FOV is 16.0 degrees, see Bell et al. 2003. They also give the resolution explicitly: 0.273/pm0.003 mrad/pixel (0.0156/pm0.0002 degrees/pixel), which is useful for this type of calculation.

You can also verify this by making a panorama (especially a 360), put in 16.8 and things go horribly wrong.

James

Thanks for the information James.

The sources available on the net are quite confusing; different focal lenghts and then different FOVs.

http://europa.la.asu.edu/pgg/greeley/cours...w/bell_2003.pdf:
The Mars Exploration Rover Athena Panoramic Camera (Pancam) Investigation
"The Pancam optics have an effective focal length of 43 mm and a focal ratio of f/20, yielding an IFOV of 0.27 mrad/pixel and a FOV of 16°× 16°"

http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1980.pdf:
The Panoramic Camera (Pancam) Investigation on the NASA 2003 Mars Exploration Rover Mission.
"The optics for both cameras consist of identical 3-element symmetrical lenses with an effective focal length of 42 mm and a focal ratio of f/20, yielding an IFOV of 0.28 mrad/pixel or a rectangular Field of View (FOV) of 16°x 16° per eye."

http://www.highmars.org/niac/education/mer/mer00.html:
Mars Exploration Rovers - About the MER PanCam
"The optics for both cameras consist of identical 3-element symmetrical lenses with an effective focal length of 38 mm and a focal ratio of f/20, yielding an IFOV of 0. 28 mrad/pixel and a square FOV of 16. 8°16. 8° per eye."

http://athena.cornell.edu/pdf/tb_pancam.pdf:
Pancam
"The optics for both cameras consist of identical 3-element symmetrical lenses with an effective focal length of 38 mm and a focal ratio of f/20, yielding an IFOV of 0.28 mrad/pixel and a square FOV of 16.8°×16.8° per eye."

It would be interesting to know what is the source of this confusion (new/existent thread?), but for me the "panorama argument" seems to be enough.

According to the Bell document. Each pixel measures 2.8 cms at range of 100 meters. The above case, the distance would be 790 * .028 meters = 22.18 meters and the height would be : 60 * .028 = 1.68 meters.

I think that the distance from Rover to Mogollon rim is not rather 93 meters as Tesheiner has told in the previous append but as 22 meters. If you the above picture, I don't seem that picture is so far as 90 meters but less as 20 meters.

Rodolfo

Yes, about 2.8cm at 100m... but not 2.8cm on the whole range from 0 to 100m.
You cannot calculate the distance to a feature by just multiplying that 2.8cm factor by the number of pixels up to the feature; you should use Parallax calculator or one of the available route maps.

According to the document of Bell posted by Jamescanvin, at the page 12. Pancam provides a spatial resolution of 2.8 cm/pixel at a range of 100 meters, which is the maximum distance that the MER rovers can be expected to traverse in one sol.

Then the measurement of 2.8 cm/pixel is valid from 1.5 meters (Pancam cannot focus lower than 1.5 meters) up to 100 meters. The document does not say at 100 but it says at a range of 100 meters.

Other thing, about the Parallax Calculator, I was playing with this and I still does not get any desired results.

http://copperas.com/merpx/

As an example, the interested Mogollon Rim is about 790 pixels from Oppy position according to the GIMP measurement on the picture I have posted previously:

MER Stereo Parallax Calculator (Joe Knapp jmk@copperas.com)

PANCAM * NAVCAM o

[790] Horizontal position of object, left camera (pixels, 0-1023)

[790] Horizontal position of object, right camera (pixels, 0-1023)

[ 1] Dimension of object (pixels)

[Calculate]

Camera: PANCAM
nl: 790
nr: 790
dim: 790

object distance: 8.2 m, one-pixel error: 0.031 m
object dimension: 181.5 cm

The object distance is at 8.2 meters? It does not coincide with any of both. 22 meters and neither 93 meters.

How do you use the parallax calculator, give us an useful example.

Thanks

Rodolfo

Rodolfo,

1) About spatial resolution: pancam (or any camera) as a fixed angular resolution i.e. the same degrees/pixel for all distances. But when speaking in terms of meters/pixel, the resolution depends on the distance. And wrt the referred paper, "at a range of" = "at a distance of".

2) How to use the Parallax Calculator: you must pick the X position (in pixels) of a desired feature on either the left and the right camera images and input that data on the web page. Example:
Pick these two images taken at the same time:
http://marsrovers.jpl.nasa.gov/gallery/all...KCP1925L0M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all...KCP1925R0M1.JPG
Select an object you want to know its distance and locate its position on both pictures:
x (left): 583, x (right): 539
It's distance, per parallax, is:
Camera: NAVCAM
nl: 583
nr: 539
dim: 1

object distance: 5.54 m, one-pixel error: 0.063 m
object dimension: 0.5 cm

Now it's up to you to do the same exercise with a feature at Mogollon Rim.
Note: Try with pancam (not navcam) pics; you'll get smaller one-pixel errors.



PS to the Admins: Fell free to move this discussion to another thread on the tech section. Do you agree, Rodolfo?

Tesheiner: Good explanation. Obrigado/Gracias

Adm, I agree to seperate the recent posts related to Pancam measurements from Erebus topic to a new topic as "Techniques to measure the distance with Pancam".

Rodolfo

The web tool: MER Stereo Parallax Calculator at http://copperas.com/merpx/
I seems that it is not be working well. I have entered different Horizontal position of object of left and right camera and press the calculate, the results remains about the same for any value such as the following:
Camera: PANCAM
1)
nl: 636
rn: 638
dim: 1

object distance: 8.35 m, one-pixel error: 0.033 m
object dimension: 0.2 cm

2)
nl: 100
nr: 100
dim: 1

object distance: 8.17 m, one-pixel error: 0.031 m
object dimension: 0.2 cm

How did you get the right results?
Are you sure that the MER Stereo Parallex Calculator from http://copperas.com/merpx does work well?
The value of 1 and 1000 pixels, obtains about the same results, between 8.17 and 8.14 meters....

I will write to the author of the above Web to inquiry about it.

Rodolfo

Here is a lookback to the Northeast to the North Erebus dunefield. From Sol 659-660, L257 color. Behind the large dune in the center is the outcrop "Four Lane", with the Erebus Highway lying beyond that.

Also included is a 3x vertical exaggeration of the center frame of that panorama.

--Bill

Does anybody know the name of the pan from this position (64KC)?

Here's a view way across Erebus. It's a big crater.

Erebus pan.

an angular fragment (at top); pushed up by nothing other than "frost-heave"?

That _is_ strange. I've been trying to figure this one out for a couple of days.

"I dunno"

---Bill

false alarm? from looking at the 3D Anaglyph, you can see the bedrock just in front of it drops off pretty steeply to the 'angular fragment', so it may be nothing other than another overhang that fell off the edge of the curb, leaving its rear sticking up in the air.

it amazing how much were missing when were not looking at the stereo views

I got bitten by that optical illusion a while back. Shadows made a rock looked like a hollow shell.

I just did a quick-and-dirty x-eyed stereo view of "the cowlick" and it is unusual in that there is differential weathering/erosion that has caused this piece flip over the edge and go tail-up. Not super-weird, but another puzzle-piece nonetheless.

I'll work up an x-eyed stereo pair this evening, unless someone beats me to it.

--Bill

Tesheiner,

here is the Erebus 360 degree panoramic view.

Taken with the L2 pancam on Sol 657 - Sol 661.

Consisting of 103 images.

jvandriel

was the "cowlick" something different than this, maybe i havent seen, care to point?

as far as anaglyphs, theyre all automated on lyle.org, under the 'synthesised imagery' section, they usually come out pretty good, though on rare occasions they are reversed Right<-->Left !

Here is x-eyed stereo pair; the feature may not be cowlick-like, but that was my first impression of it and the name sticks.

I need to automate my stereograms; I do them the old-fashioned cut-and-paste way.

---Bill

Again from Sol660 Erebus image campaign: R1 mosaic (half res and strech x5).
Click to view attachmentClick to view attachment
... now I see it!