I read the google android api and was confused about what a map tile is as the api described how google map handles "downloading map tiles".
(Src)-https://developers.google.com/maps/documentation/android/map. Can someone give a quick overview of what a map tile is. Just a section of the map that fits a device screen?
The section of the map that is rendered on the device screen can consist of many tiles. Basically, the map is segmented into multiple tiles based on the zoom level.
From OpenStreetMap-Wiki:
square bitmap graphics displayed in a grid arrangement to show a map.
From Google Maps Android API:
The Google Maps API breaks up the imagery at each zoom level into a
set of square map tiles arranged in a grid. When a map moves to a new
location, or to a new zoom level, the Maps API determines which tiles
are needed and translates that information into a set of tiles to
retrieve.
The tile with coordinates (0,0) is always at the northwest corner of
the map, with x values increasing from west to east and y values
increasing from north to south. Tiles are indexed using x,y
coordinates from that origin.
At zoom level 0, the entire world is rendered in a single tile. Each
zoom level increases the magnification by a factor of two. So, at zoom
level 1 the map will be rendered as a 2x2 grid of tiles. At zoom level
2, it's a 4x4 grid. At zoom level 3, it's an 8x8 grid, and so on.
Bing Maps Tile System:
Related
I am showing the CameraPosition Zoom in a label on Mapview, and using a custom raster tiles' source and have noticed that the zoom level of tiles being shown on mapview and the zoom level of camera are actually different (For example, at Camera Zoom 14.something i was getting tiles for zoom level 16).
Does somebody know why could that have happened?
In order to maximize imagery sharpness throughout the fractional zoom range, raster tiles transition at half-zoom levels in Mapbox SDKs. So for instance, a z14 raster tile is used for the range [z13.5, z14.5).
(If you are using 256 pixel raster tiles, you may also observe a difference of +/- 1 zoom level between the zoom level reported by the map, and the zoom level in tile URLs. This is because Mapbox GL zoom levels are calibrated against 512 pixel tiles. 256 pixel tiles are therefore loaded at +1 z relative to the map zoom.)
I have been searching in the documentation and throughout google. I would like to know if it is possible to place an image over the map the api comes from to use something else as a visual but with the maps gps functionality. Does anyone know if this is possible?
You can use two types of Overlays:
TileOverlays (reference)
A TileOverlay defines a set of images that are added on top of the base map tiles. You can also use tile overlays to add extra features to the map by providing transparent tile images. You need to provide the tiles for each zoom level that you want to support. If you have enough tiles at multiple zoom levels, you can supplement Google's map data for the entire map.
GroundOverlay (reference)
A ground overlay is an image that is fixed to a map. Unlike markers, ground overlays are oriented against the Earth's surface rather than the screen, so rotating, tilting or zooming the map will change the orientation of the image. Ground overlays are useful when you wish to fix a single image at one area on the map. If you want to add extensive imagery that covers a large portion of the map, you should consider a Tile overlay.
I am not using Google maps or Openstreet maps. I am using another third party custom maps which do not provide any bounding box classes or methods. So What i want to achieve is to zoom to fit all markers on the map or zoom to route drawn on map. Like Google provide LatLngBounds bounds = mMap.getProjection().getVisibleRegion().latLngBounds; classes and OpenStreetMaps provides zoomToBoundingBox() to achieve this functionality. I only have latlng points and map dimensions width/height. How can i calculate bounds or bounding box zoom level for markers or route drawn on map to fit it to screen? Any formula or mathematical calculations?
I have tiles downloaded from Mobac tool, with the source being Openstreet mapQuest.
Given that we may not have tiles for all positions at a higher zoom level, when we scroll, areas that are missing tiles result in a null grid or stretched images of lower zoom-level tiles.
How can I restrict scrolling to only a given bounding box and zoom level?
Implementing MapListener interface, I overrode the OnZoom function. Depending upon current zoomlevel and the points visible on screen, the scrollable boundingbox can be set by calling mapView.setScrollableAreaLimit.
I have a MapView with one overlay. Overlay renders tile based map over the MapView. I use MapView.getZoomLevel() to retrieve current zoom level for Google map and for my tiles. Everything works just perfect, but only if user don't zoom the map using multitouch gestures. As I understand, the MapView control don't render actual tiles during zooming process, but just show stretched screen content. So, the question is - How to get this scale ratio which I can use to render my tiles exactly in same way as Google do?
Thank You!
Although the method MapView.getZoomLevel() isn't aligned with zoom changes animation and multitouche, the methods MapView.getProjection().fromPixels() and MapView.getProjection().fromPixels() are.
So you have several option to adress the issue. From the methos above, you can find the direct (x,y) coordinates (and size) where to render the tiles or you can find the zoom ration using something like:
int lonSpan = projection.fromPixels(0,mapView.getHeight()/2).getLongitudeE6() -
projection.fromPixels(mapView.getWidth(),mapView.getHeight()/2).getLongitudeE6();
which gives you the longitude span at map vertical center. Then, you divide the value after zoom starts from the value before zoom starts.
Regards.