APF Numbers: What are they - Can we use them?

• by Kitharode moderator

  The Object images each have an APF number. Can we make use of this number in any way? How do we find them? What's 'APF'? etc, etc. Thanks Everybody.

  Posted March 18, 2013 3:53 PM

• by JellyMonster

  I'm glad someone has brought this topic up. What I normally do now, is first choose an image as a starting point, then change the last alphanumeric to something else. So for instance, APF00004tg, APF00004tz and APF00004t5 are all of a similar nature, in this case wild spiders! However, APF00002d7 and APF000023q join up (with an overlap) even though the last two alphanumerics are quite different!

  Posted March 18, 2013 8:21 PM

• by Kitharode moderator

  Thanks JM. That's a good start for me and very useful. Perhaps there's a 'bit of a formula' we can find out about that'll help us out. I'll ask Meg, she might give us a link to visit or even post the answer. I'd love to be able to see a few of these things put together, even if they weren't right next door. Just for a feel of the wider view. I'm hoping to learn where a few things live on Mars so I can track them on my mars map.

  When you say you 'change the last alphanumeric' I'm happy with that, but how would I find this new image. Do I google it or do I find it around here somewhere?

  Posted March 18, 2013 10:54 PM

• by wassock moderator

  Sometimes if you increase the 2nd last 'digit' by 3 and then check through the images immediately above and below you'll find the same place for a different time. Helps if you have a good strong feature to look for.

  Try these 3 from the chicken/egg thread in science objects - APF00003ea and APF00003he (and APF00003lp

  Posted March 18, 2013 11:14 PM

• by Kitharode moderator

  Thanks wassock. (I was beginning to miss you).

  So when I find an image, I see its APF number and I can change it, in my head or on paper at least, say APF00xyz to APF00xtu, but I'm not clear what I do with the new number. I'm guessing I 'search' somewhere or type it in a box?

  Posted March 18, 2013 11:30 PM

• by wassock moderator

  Kith the APF number is the last part of the URL for the image discussion page, just change the number in the box top o ye browser and hit return. Simples

  talk.planetfour.org/#/subjects/APF00003ea

  Posted March 18, 2013 11:55 PM

• by Kitharode moderator

  Doh! Look at the stupid Kitharode meerkat. Of course it is. Many thanks guys. If you suss out anything else please do post it for me. I've got what's been said so far, so just one more thing.

  Change last alphanumeric, get similar image/region - useful. Change last three, can get images that overlap - more useful. But it's not a simple 00123 to 00456 overlap. JM's overlaps were 002d7 and 0023q. How can we possibly know what to change the numbers to if we want an overlap? Is this where the 'bit of a formula' comes in or do you think that's an unknown/doesn't exist? Or maybe you've worked it out .. ?

  Posted March 19, 2013 12:25 AM

• by wassock moderator

  Kith, think that plus 3 like that gives you a different point in time the three pics above are all the same spider see the chicken egg thread for the dates but they are in date order as listed above

  NB the interval is only approximate and you need to cycle through a few to find your match.

  Posted March 19, 2013 12:44 AM

• by Kitharode moderator

  OK, this is good stuff and the picture becomes much clearer. This'll be a useful thread for me to bookmark and pass around too. So if I've got it right (at last), a change in the last alphanumeric gives me something close-by (a location thing) whereas changing last three alphanumerics, and perhaps a bit of a flick through, gives me same place at different times(ish). Close enough?

  Posted March 19, 2013 1:27 AM

• by mschwamb scientist, translator

  Hiya,

  APF ID is the unique internal identifier that we use to label cutouts from HiRISE images so we can store them in the Planet Four database used to run the site. It stands for Asset Planet Four. In our case an asset is an image. All Zooniverse projects label their assets ( images, light curves, etc) in this manor. So for Planet Hunters for example it's APH number instead of APF id.

  A HiRISE image is much much larger than the images we show on the site. The HiRISE image is cut into 81 images (9 rows x 9 columns) The cutouts (which each has a unique APF id) are 840 × 648 pixels with a 100px overlap in both the x and y directions from the previous cutout tile. I don't know how the APF ids are probably sequential according to the input list but I don't know how that was ordered. So sometimes it will relate to the same HiRISE image as you're talking sometimes it will be referring to a completely different image.

  I believe that the APF id doesn't necessarily correlate to time, I think it's just alphanumeric string. I will talk to the team about the possibility of making it easier to go from APF ID to full HiRISE image on Talk. The reason we don't want to reveal that information in the main classification interface is because then someone may then google or search for the image on Talk and then their perspective will be biased or influenced by other people's comments and we really want the first impressions from the classifier.

  Cheers,

  ~Meg

  Posted March 19, 2013 2:27 AM

• by Kitharode moderator

  Now that's what I call a good answer. Thanks Meg. I can quite understand why some things may need to be 'eyes only' for all sorts of reasons. Better keep an eye on us and make sure we're not speaking out of turn, eh? I don't think we do generally. 😃 Thanks Muchly.

  Posted March 19, 2013 2:50 AM

• by JellyMonster in response to Kitharode's comment.

  Try these 3 from the chicken/egg thread in science objects - APF00003ea and APF00003he (and APF00003lp) - (wassock's quote)

  An excellent example wassock.

  whereas changing last three alphanumerics, and perhaps a bit of a flick through, gives me same place at different times(ish) - (Kitharode's quote)

  Kitharode, I think you mean the last two alphanumerics.

  Posted March 19, 2013 8:14 AM

• by Kitharode moderator in response to JellyMonster's comment.

  Oops! Probably do. There's a few 2's and 3's in the thread so might well get mixed up. Ta.

  Posted March 19, 2013 11:52 AM

• by mschwamb scientist, translator

  I should also say, if you want the link to the full HiRISE image for a given APF id, any member of the science team can likely dig that out of the copy of the Planet Four database that we have.

  Cheers,

  ~Meg

  Posted March 20, 2013 10:06 AM

• by JellyMonster in response to mschwamb's comment.

  Yes, that might be useful Meg, thanks.

  Posted March 20, 2013 10:18 AM

• by JellyMonster in response to mschwamb's comment.

  A HiRISE image is much much larger than the images we show on the site. The HiRISE image is cut into 81 images (9 rows x 9 columns).

  Meg, most of the HiRISE images I have seen are long skinny things, certainly not 9 x 9... more like 9 x 45?

  Posted March 26, 2013 10:39 AM

• by mschwamb scientist, translator

  Thanks for bringing that up. You're correct is should be something like 91 rows and 5 columns of cutouts. I was just reading the max value of the database for the cutout indexes which tell you which column and row the cutout comes from. Looks like we might have a bug in the code that puts that info the database. That started recounting after 9. It doesn't change anything (since positions relative to the full HiRISE frame is saved in a few different ways), but we should update the index values correct positions.

  Cheers,
  ~Meg

  Posted March 26, 2013 6:21 PM

• by wassock moderator in response to mschwamb's comment.

  Meg

  The full grey scale images are 5 km across, so I assume you are talking about the strip down the middle that comes out in colour?

  Posted March 26, 2013 9:08 PM

• by mschwamb scientist, translator in response to wassock's comment.

  Or at least one image I was looking at that was color.

  ~Meg

  Posted March 27, 2013 1:13 AM