Editing 2920: Survey Marker
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==Explanation== | ==Explanation== | ||
− | Cueball and Megan have found a {{w|survey marker}} on the ground. Survey markers such as these are used as reference points for the {{w| | + | {{incomplete|Created by a GUIDED MISSILE THAT MISSED THE TARGET DUE TO COORDINATE DRIFT - Please change this comment when editing this page. Do NOT delete this tag too soon.}} |
+ | Cueball and Megan have found a {{w|survey marker}} on the ground. Survey markers such as these are used as reference points for the {{w|North_American_Datum|NAD 83 and NAVD 88}} geodetic reference systems, and the {{w|U.S. National Geodetic Survey}} has a database storing the coordinates of these markers. However, those two systems are being replaced by the {{w|National_Spatial_Reference_System#Datum_of_2022|New Datums of 2022}} (delayed to 2024-2025), which is primarily based on satellite systems and gravimetric models. | ||
− | When they update the database in the comic | + | When they update the database, in the comic Cueball's position, both horizontal and vertical, changes to compensate, leaving him panicking in mid-air. In reality, updating a database to change the coordinates of a location would not physically move items at the location.{{Citation needed}} Arguably, if they did, no-one would much notice, since everything surrounding them should similarly move simultaneously to its corrected position as well. However, this shifting does not seem to apply to Megan. This might be because she is still standing next to the survey marker, while Cueball is standing at the point in the database; Cueball's comfort in being at an ''exact'' known location has opened up an unexpected vulnerability. Or perhaps it is simply due to Megan being prepared for the update unlike Cueball. |
− | The title text refers to NAD 83 being around 7 feet off. This probably refers to the difference | + | The title text refers to NAD 83 being around 7 feet off. This probably refers to the 7 foot difference in the positioning of the centres of the notional Earth ellipsoids used as the basis for NAD 83 and {{w|World Geodetic System|WGS84}}. |
Absurd outcomes from differing survey standards was also the topic of [[2888: US Survey Foot]]. | Absurd outcomes from differing survey standards was also the topic of [[2888: US Survey Foot]]. | ||
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:Cueball: If I stand on it, they know where '''''I''''' am. | :Cueball: If I stand on it, they know where '''''I''''' am. | ||
− | :[Cueball and Megan | + | :[Cueball and Megan looks up at each other.] |
:Megan: But the NAD83 and NAVD88 datums are getting replaced soon. That marker's coordinates could shift by like 5 feet. | :Megan: But the NAD83 and NAVD88 datums are getting replaced soon. That marker's coordinates could shift by like 5 feet. | ||
− | :[Megan is looking down at her phone in her hand, standing in the same place in relation to the marker. Cueball is now floating in the air behind her | + | :[Megan is looking down at her phone in her hand, standing in the same place in relation to the marker. Cueball is now floating in the air behind her 5 feet above the ground, while flailing with his arms and legs (as shown with three small curved lines at the end of either arm and above and below him.)] |
:Megan: Oh look, it just got updated. | :Megan: Oh look, it just got updated. | ||
:Cueball: '''''Hey! Put me back!''''' | :Cueball: '''''Hey! Put me back!''''' |