Geolocating a random island using geometry and CUDA programming

(yassa9.github.io)

113 points | by yassa9 2 hours ago ago

27 comments

  • NKosmatos an hour ago

    Excellent write up and an enjoyable read! Reminds me of the “good old times” where posts on HN were written by humans and with a specific writing style like yours. You could’ve used a little bit more of geoguessing to narrow down results, or do a brute force visual check on the last hundred or so ;-)

    • yassa9 38 minutes ago

      yea, thanks :D , I used a tiny idea from geoguessing, that I banded the search on islands only in latitude between -30 to +30 deg. based on the sky and the tropical vibes in the img , and it worked !

  • bmurray7jhu an hour ago

    For drones and missiles, this technique is known as Terrain Contour Matching. If terrain contour are measured optically, navigation is independent of RF jamming, unlike GNSS.

    https://en.wikipedia.org/wiki/TERCOM

    • yassa9 an hour ago

      oh, wow, I didnt know that existed, thank u, sure gonna look into it

  • o4c 8 minutes ago

    Really great article! OP, you did an awesome job breaking down a complex problem into manageable chunks and synthesizing the solution.

  • phalanxx 41 minutes ago

    What do you mean by no LLM generation if an LLM did all the coding based on reading through the .py files? Pangram isn't kind to "your" text either.

    • yassa9 27 minutes ago

      I meant the blog itself, the writeup, the steps and the walkthrough all by hand , the final code u see is llm refined, of course, I wont publish my messy and spaghetti files with much tests, failures and dead ends, also vizualizations functions to produce that green maps , and faulty versions of them

      but you are right, I should add that

      • StilesCrisis 20 minutes ago

        Just by reading your actual messages it's easy to see that you didn't write the blog post entirely by hand.

    • StilesCrisis 21 minutes ago

      "No EXIF, no GPS, no camera make or model."

      Yeah, a human definitely wrote this. Nothing fishy here. (Why would the camera make or model matter???)

      • yassa9 10 minutes ago

        ok, if u came with the whole conclusion by only this line, ok , but to answer u, ( I hate to justify myself , but have to ) I started writing the blog after I started solving another challenge from gralhix : https://gralhix.com/list-of-osint-exercises/osint-exercise-0...

        and the part of the solution came from the metadata, the camera model, you can check urself, so when I came back to write the blog, it just came by flow,

      • voidUpdate 9 minutes ago

        If you know the camera make and model, you might be able to get lens parameters and get better estimates of real world geometry from the image

        • yassa9 6 minutes ago

          yea thank u, that's another part, but mainly it would hard although knowing that, because you need to know elevation of the drone or the camera, which is also extremely difficult (I already mentioned that in the blog)

  • lexlambda 2 hours ago

    OpenStreetMap data really is a godsend for such OSINT purposes. Works much better in populated areas too, with more features like roads, shops, electric lines that can be used to search.

    • yassa9 an hour ago

      yea , heard about them before, but didnt know that whole treasure till I really used it , impressive

  • ape4 31 minutes ago

    What about tides? Would the outline of the island be different based on the time of day.

  • cecinuga 2 hours ago

    I read all the process, literally awesome, i don't do OSINT (i know only what is this) and i think that's very cool

    • yassa9 2 hours ago

      thaaank you !! Its my first ever challenge to do, and yea, I really found my passion

  • hno8a34nwn 18 minutes ago

    This is the real takeaway

  • bitcurious an hour ago

    It’s interesting that most top contenders don’t pass the eyeball halo check, seems like there’s room to optimize that filter in code.

    • yassa9 an hour ago

      yea, good observation, my guess is its the data more than the filter. OSM coastline polygons are generalized to different degrees depending on who traced them and from what imagery, so the fine shape detail a halo check would key on often is not in the geometry at all.

      I observed that at the end, didnt push on it further though. It already passed and I was super exhausted

  • piterrro 2 hours ago

    really impressive, could that be the way to locate yourself without GPS? assuming we know more/less where we are

    • yassa9 an hour ago

      yea, search about geoguessing on youtube, people like Rainbolt, https://www.youtube.com/@georainbolt

      they literally memorize and get patterns of every possible road, place, map of any area (scanned by google earth), getting exact coordinates from single image, and play competitions and world cup based on that

      they do really nice videos about finding places in old photos people ask for

  • hhh 2 hours ago

    great blog and great writeup

    • yassa9 an hour ago

      thannks, really grateful :D

  • grodes an hour ago

    impressive

  • ohyoutravel an hour ago

    > NOTE: this is a genuine human work, didnt use LLM generation.

    A million upvotes from me.

    • yassa9 an hour ago

      haha, thanks :D I was hesitant to whether write it or not, but I really really despise llm generated posts and blogs and im glad someone appreciated it