3. List of terms for understanding
Maplat principles (coordinates)
Terms Meaning Accurate map Inaccurate map
merc EPSG:3857 (Web
Mercator)
EPSG:3857 EPSG:3857
xy XY in each coordinate
system
EPSG:3857 XY starting point at the
top left of the image
(pixel coordinates when
not scaled)
sysCoord Convenience
coordinates for
processing with the
map API (coordinates
used to set up marker
pins in the original map
API)
For OpenLayers,
EPSG:3857
For OpenLayers,
EPSG:3857 for
convenience (not
related to actual
geographic
coordinates)
3
Quote from https://github.com/code4history/MaplatCore/issues/19
4. List of terms for understanding
Maplat principles (area)
Terms Meaning Note
size Display range in pixel width, height
radius Display range radius in sysCoord
definition
Calculated based on a circle half
the size of the size, not the
full ”size” range
viewPoint Center point + zoom + rotate in sysCoord
definition
sysCoord
s
5 points in sysCoord definition (center,
top, bottom, left, right)
xys 5 points in xy definition
mercs 5 points in merc definition
4
Quote from https://github.com/code4history/MaplatCore/issues/19
5. Maplat map switching principle 5
Map coordinates A
Map coordinates B
Get center,
zoom,
rotate
viewPoint2SysCoords
SysCoords xys
mercs
Set center,
zoom,
rotate
SysCoords xys
sysCoords2Xys xys2Mercs
sysCoords2ViewPoint xys2SysCoords mercs2Xys
6. How to use several Maplat libraries (1) 6
Get center,
zoom,
rotate
SysCoords xys
mercs
Set center,
zoom,
rotate
SysCoords xys
sysCoords2Xys xys2Mercs
xys2SysCoords mercs2Xys
MaplatCore
Internally used
MaplatTin 5 times
Internally used
MaplatTin 5 times
Map coordinates A
Map coordinates B
viewPoint2SysCoords
sysCoords2ViewPoint
8. Maplat
MaplatCore
MaplatSwitch
8
UI
Make this process independent
as MaplatSwitch in the future
How to use several Maplat libraries (3)
Foreground map
OpenLayers
Background map
OpenLayers
Map display control
Coordinates transformation
9. How to realize Maplat 9
Overlay Switch
※ If you want to use OpenLayers as a map API, it is already implemented in Maplat/MaplatCore, and
you can optionally switch between Overlay/Switch, so assume that you want to use other map APIs.
Foreground map
Map API
Background map
Map API
Map API
MaplatCore or
MaplatSwitch
Realtime control
MaplatCore or
MaplatSwitch
Coordinates transformation
Switch displaying map