Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: On the integration of location and data
    From: Frank Reed
    Date: 2009 Nov 8, 20:45 -0800

    George H, you wrote:
    "That was the claim that presumably Frank is repeating, as he has linked our 
    attention to it once again. Does he still maintain those words?"
    
    As I said to you back then, George, the pointing accuracy is not a critical 
    matter. I said this to you again and again and again. I linked to that post 
    to repeat my point about using this technology to boost celestial navigation 
    education. It's going to be revolutionary. The number of people who can 
    identify the brightest two dozen stars on any night may be ten times higher 
    in two years than it is today (and I don't mean people who can point their 
    phones, click a button, and read the screen... I mean people who have done 
    that enough times that they can walk down a street and say "Oh look... that's 
    Vega... I learned that from my phone last week").
    
    And you wrote:
    "At the time, I expressed my usual scepticism. It seemed too good to be true. 
    It was. Being entirely dependent on the local magnetic field, its pointing 
    accuracy could be no better than the local magnetic field was. The ensuing
    discussion flows under the threadname "learn the stars, by phone"."
    
    Yes, alas, there were quite a few pointless posts in that thread distracting 
    from the original subject. That original subject must really bug you, George. 
    Is the very thought that ordinary people, mostly young people, might be able 
    to learn the names of the navigational stars from a mobile phone somehow 
    discomforting to you? You appear to be obsessed with pointing accuracy. So 
    let me repeat, POINTING ACCURACY IS NOT A MAJOR CONCERN FOR THIS APPLICATION. 
    Sorry to yell at you, George, but you do sometimes need it.
    
    And you wrote:
    "On investigation, it turned out that Celestron had quickly relaxed that spec 
    to a pointing precision of 0.5 to  "2 to 3 degrees", interpreted as 3 degrees 
    by a Celestron distributor."
    
    And just a reminder, George, you have still not even bothered to define 
    "pointing precision". How strange to worry so much over something that you 
    have not defined...
    
    And you wrote:
    "We were assured that the instrument could detect the presence of local 
    magnetic material, and give a warning, before significant error occurred. 
    That seemed unlikely; see recent results, below."
    
    It can do so, yes. Does it do it perfectly? No. Why should it?? Any child can 
    break a toy. And sadly, many children can only think of demonstrating that 
    talent when presented with a new toy. The SkyScout does indeed give a warning 
    under many circumstances. That it is not perfect is to be expected, and it's 
    hardly worth mentioning. Have you once again confused an educational 
    observing tool with a measuring instrument??
    
    And more:
    "So that implied that the pointing could be off-axis by 3 degrees, and the 
    instrument could still meet its revised spec., a target width 6 degrees 
    across (about 3 fingers at arm's length). Celestron claimed that their 
    database included 50,000 sky objects: that target might contain 34 of them."
    
    Wow. You really are very confused by the purpose of this machine, aren't you? 
    Let's take two examples from this database (actually from a similar database 
    on a mobile phone version of this idea but almost certainly included in the 
    Skyscout database): the star Vega and the "center of the Milky Way". The 
    first object is one of the very brightest stars in the night sky. The second 
    is quite invisible from the Earth in optical wavelengths. 
    
    Including the first object, Vega, in the database is an obvious choice. It's 
    there because a backyard observer might well point the device at "that bright 
    star up there" and click the "Identify" button. Now it's possible, just 
    barely possible, that some very bad software designer would ask the software 
    to start with the faintest object in the database near the pointing location 
    and indicate that object as the identity of the bright star in the sky. And 
    in that case, the pointing accuracy would be terribly important, and your 
    point would be made. But guess what, George -- people aren't idiots. The 
    software starts with (or appears to start with) the brightest object in the 
    indicated direction when it is in Identify mode. 
    
    Why is the center of the Milky Way in the database? We can't see it. This 
    object falls into the second type of functionality found in the SkyScout and 
    similar devices. That's the "Show me" mode. You select an object, like this 
    one, from the database on-screen and then you hit the "Show me" button 
    (whatever its equivalent is on Skyscout). It then responds with arrows which 
    will guide you to that part of the sky until that spot in Sagittarius is more 
    or less centered in the field of view. The software can then tell you "all 
    about" the center of the Milky Way. It's educational, and it's very 
    entertaining for many people to know that they are looking right at it even 
    though it's just a blank patch of sky. It's literally like a planetarium show 
    in the palm of your hand.
    
    And you wrote:
    "In the absence of any magnetic perturbation, no doubt that instrument, or 
    some sort of fancy-phone that works the same way, might do a reasonable job 
    in pointing precision"
    
    Fine. That's all that's required. Let me repeat that a little louder for you: 
    THAT IS ALL THAT'S REQUIRED. 
    
    And you wrote:
    "though not, unfortunately, in a moving envirenment at sea or on land."
    
    Certainly not with current implementations of this technology. To deal with 
    accelerations would require a more sophisticated inertial system if such 
    functionality was really desirable. And if I did not see people playing "Wii 
    Bowling" every night in local bars, I might contend that the possibility of 
    miniature inertial motion analysis in a handheld device was science fiction, 
    something for the 22nd century, not this one. But they do. That said, WHY 
    WOULD YOU CARE? Why would operation in a "moving environment" be desirable? 
    What difference does it make that you can't do this while flying down the 
    parkway in your car and accelerating around curves? Is that really an 
    important environment for learning the names of the stars and, perhaps, 
    pointing out the location of the center of the Milky Way??
    
    And here's George's big coup de grace for this technology:
    "With a firm footing in the open air, away from vehicles, steel-framed 
    buildings, a pyrites seam, or steel-framed spectacles, it might be fine as 
    long as the magnetic mapping gets updated periodically. Elsewhere, how can a 
    user be sure that it's unaffected, in a world that's rife with iron and 
    steel?
    Not by relying on the indicator that warns of the presence of magnetic 
    material. An attempt, not by me, to try fooling it, showed that it was 
    possible, with care,  to approach a Skyscout, from East or West, with a small 
    magnet held horizontally, to within 10 cm, and thereby twist the indicated 
    azimuth by all of 50 degrees, before it indicated presence of magnetic 
    material!"
    
    LOL. It's a good thing we have you here, George, to keep us from putting 
    magnetic compasses in our mobile phones. Those engineers at Apple, Motorola, 
    Nokia, and the others owe you a debt of gratitude. You have proved that the 
    software which they have running on their phones using magnetic compass data 
    cannot possibly be running on their phones using magnetic compass data. It 
    cannot be. I presume that reality, having been observed by you, has now 
    collapsed into an eigenstate where such devices and such software no longer 
    exist. Poof!
    
    Or maybe not. Maybe reality is what it is, and the problems you feel you've 
    found simply aren't relevant to "useful" functionality. Do you suppose that's 
    possible, George?? As for being able to "break" the behavior of the Skyscout 
    by carefully bringing a magnet up to it, well, yes, you can break any toy. 
    Does that mean you could never find any pleasure in using one, knowing that 
    it is imperfect and capable of being fooled?? Do you contend that no one 
    could learn the stars this way because some gremlin might be sneaking up on 
    them with a magnet?? 
    
    George, you wrote:
    "In his recent posting, Frank appears to be rowing back from magnetics"
    
    Not in the slightest. Please do not put words in my mouth. The mobile phones 
    using GPS positions and magnetic compasses to point the user to astronomical 
    objects using specialty software currently EXIST. Why would I be "rowing 
    back" from reality?
    
    And you quoted me saying that the technology 
    "generally implies a built-in magnetic compass. There's a way around this in 
    major cities if you use some sophisticated processing (which can occur 
    server-side) to take the image, the GPS (or wifi) location data and then 
    figure out direction based on the buildings seen and maybe even using shadows 
    if it's daytime. That combined with the simple inertial sensors in many 
    phones would yield orientation without a magnetic compass."
    
    Yes, I was pointing out that it might be possible to do some of this 
    "augmented reality" stuff that they've been talking about by turning the 
    tables. Rather than using the compass to get direction, we could use 
    astronomical cues or obvious landmarks to get direction. Shadows are rather 
    easily defined in photos in urban environments. If the phone knows the 
    location and date and can detect a long shadow pointing in a particular 
    direction, then it can get orientation EVEN WITHOUT a built-in compass. This 
    would require a fair amount of image processing using the camera's live video 
    which poses certain privacy and security issues (!!!) so that may be a long 
    time in coming (read five years instead of two).
    
    And George, you concluded:
    "Is Frank really serious? In what circumstances could such technology 
    conceivably aid a viewer of the night sky? We've had many absurdities on 
    Navlist, but this one ranks near the best."
    
    George, for the life of me, I cannot fathom how you become so confused by the 
    things I say. Do you REALLY have such trouble reading my sentences? Or are 
    you just trolling (in this case, "trolling" means posting absurdities just 
    for the fun of being annoying)?
    
    -FER
    
    
    
    
    
    --~--~---------~--~----~------------~-------~--~----~
    NavList message boards: www.fer3.com/arc
    Or post by email to: NavList@fer3.com
    To unsubscribe, email NavList+unsubscribe@fer3.com
    -~----------~----~----~----~------~----~------~--~---
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site