Map and Satellite picture difference

[+Jayeffel]

When looking at a cache on Geocahing.com I click on Directions to see where the cache is geographically. I noticed something that seems odd to me the other day.

 

I recently placed a cache after determining the coordinates were accurate. When. using the "Direction" option on the cache page in the Map view it shows the cache at a house next to where the cache actually is. It shows a shadow image of the buildings. The building on the corner of the cache site is a laundry, on this Map option it shows the name of  laundry superimposed on the house  mentioned earlier. the cache is between the laundry and the house. 

 

When choosing the  Satellite view, the cache spot is shown where the cache actually is, or very close, Not at the house. I am not not sure why this is. I guess magic. 

 

Another interesting part of this cache is I had one there a few years ago and the same coordinates were used, but the satellite view alway showed the cache across the street, update coordinate did not help and it was archived. The only difference in coordinates was the last two digits in the longitude- .686 and .688. thr4 street runs north and south so the different ewould seem to be in the Latitg de number. 

 

Just curious, if it is working why worry!

[+ecanderson]

Actual WGS84 location vs. various satellite and mapping companies' products aren't always exactly on the same page, so to speak.  While this situation continues to see improvements in alignment, it's not all perfect everywhere out there.  Some areas seem to be spot on, others not so much.   Depends upon where you are and whose products you are using.

[+The A-Team]

On ‎2‎/‎27‎/‎2020 at 7:16 AM, Jayeffel said:

Another interesting part of this cache is I had one there a few years ago and the same coordinates were used, but the satellite view alway showed the cache across the street, update coordinate did not help and it was archived. The only difference in coordinates was the last two digits in the longitude- .686 and .688. thr4 street runs north and south so the different ewould seem to be in the Latitg de number.

 

Where a cache appears on any particular map is largely irrelevant. Like ecanderson said, various maps will have different offsets, so the cache would never appear to be in the same location across all maps. In the end, for the most part, people aren't using the map to find the cache anyway. The most important thing is to get the most accurate coordinates you can.

[+fizzymagic]

On 2/27/2020 at 7:16 AM, Jayeffel said:

 Another interesting part of this cache is I had one there a few years ago and the same coordinates were used, but the satellite view alway showed the cache across the street, update coordinate did not help and it was archived. The only difference in coordinates was the last two digits in the longitude- .686 and .688. thr4 street runs north and south so the different ewould seem to be in the Latitg de number.

 

First of all, if the street runs N-S then the difference between the two sides of the street is a longitude difference.  Second, longitude at your latitude is about 4 feet per thousandth, so a difference of .002 is about 8 feet.   Finally, the geo-registration of Google images, while quite good, is by no means perfect.

[+hzoi]

You want really inaccurate, check out the difference between sat and street maps in China.  They force a map offset for security purposes, with comical results.

[+NYPaddleCacher]

6 hours ago, hzoi said:

You want really inaccurate, check out the difference between sat and street maps in China.  They force a map offset for security purposes, with comical results.

 

When I last looked the offset was several hundred feet.   A cache that I found in Old Summer Palace in Beijing appeared to be in the middle of the lake on sat maps.  

[+NYPaddleCacher]

Satellite imagery has greatly improved in the last several years.  I remember a cache that I had found in Costa Rica that was located in an area where the sat maps were showed nothing but clouds.  The street view showed it to be just off the road where there was a sharp turn.   The was a wide pull-out area there and the cache was located about 25 from a steep drop off into a creek, but there was not way to see that from the sat map.

 

A couple of years later Google started implement sat maps that would stitch together images taken different times of the year, resulting in sat maps that were mostly cloud free.  

 

The resolution of the satellite photos in some area has significantly improved.   I remember looking at satellite imagery for a town I was visiting in Tanzania in 2010.   The resolution was so poor that many of the buildings in town were not even recognizable as buildings.  

 

That said, this is a game played globally, and satellite imagery is not consistent worldwide, relying on satellite imagery alone could be problematic for caches placements in some areas.

[+Viajero Perdido]

40 minutes ago, NYPaddleCacher said:

Satellite imagery has greatly improved in the last several years.

 

Has it ever!

 

And not just Google.  In the world of OpenStreetMap, we have imagery from Bing, Landsat, Maxar, MapBox, and Esri (but pointedly not Google) available for mapping.  If you've noticed the quality of OSM mapping getting better, it's because of many people tracing from - finally - high-quality imagery.

 

So the map will catch up.

[+barefootjeff]

4 hours ago, NYPaddleCacher said:

The resolution of the satellite photos in some area has significantly improved.

 

A couple of years ago, Google downgraded the resolution of their satellite images for much of the New South Wales Central Coast region. There's still some parts at the original resolution but the rest is just a blur. Here's an example at the border, with the old high resolution imagery on the right and the new "improved" imagery on the left:

 

 

I don't know whether this was done as a cost-cutting exercise or because of "privacy" or "security" issues, but the low-resolution areas seem to be growing. Fortunately there's a mapping service provided by the state government (SIX maps) that still has high resolution images of this region.