I'm using openlayers to create a map of a body. It shows the mri-scan of a person en on there are a lot of markers.
Totally zoomed out, there's a lot of whitespace (or in my case black space as the background is black) I've set up openlayers with the extent parameter, so users are not able to pan further than the image is big. However when the user hovers over the whitespace around it, and scrolls to zoom, the image is zoomed into based on the position of the cursor, so the body is out of view. Once the user starts panning again, the extent comes in to play and jumps back to the edge of the image.
Is there a way to disable zooming in/out when the cursor is outside the extent? Or if that is not possible, how can I trigger a move/pan so it jumps automatically to the edge of the image?
EDIT 14/12/2016: Created a JSFiddle to illustrate the issue.
And the code that is running there:
var pbm = {};
pbm.vars = {};
pbm.vars.extent = [0, 0, 1536, 5120];
pbm.vars.projection = new ol.proj.Projection({
code: 'xkcd-image',
units: 'pixels',
extent: pbm.vars.extent
});
/**
* initMap
* --------
* triggered by pbm.parseCases!
* outputs the bodymap to the #body-div
* this functions needs all the other ol-elements to work!
*/
pbm.initMap = function(){
pbm.map = new ol.Map({
layers: [
new ol.layer.Image({
source: new ol.source.ImageStatic({
url: 'https://s3-eu-west-1.amazonaws.com/norvell-philips/bodymap-static-hiress.jpg',
projection: pbm.vars.projection,
imageExtent: pbm.vars.extent
})
})
],
target: 'body',//Div#body
view: new ol.View({
projection: pbm.vars.projection,
center: ol.extent.getCenter(pbm.vars.extent),
zoom: 2,
maxZoom: 5,
minZoom: 1,
extent: pbm.vars.extent
}),
renderer: 'canvas',
controls: ol.control.defaults({attribution:false, rotate: false, zoom:false}),
interactions: pbm.vars.interactions
});
}
$(document).ready(function(){
pbm.initMap();
});
This is a bug that was recently fixed. The first release to contain the fix will be v3.21.0. The ticket with links to the fixes is #5824.
Related
I have a list of coordinates I want my code to pan through. I can place view.animate and do it once to pan from my current center to the first coordinate but not to keep cycling through the list. Any ideas? I got the idea from this https://openlayers.org/en/latest/examples/animation.html.
var coordinates = [london, moscow, istanbul, rome, bern]; (they have their coordinates)
var view = new ol.View({
center: istanbul,
zoom: 4
})
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
})],
loadTilesWhileAnimating: true,
view: view
});
coordinates.forEach(function(element) {
setTimeout(view.animate({
center: element,
duration: 2000,
}), 10000);
});
You have a basic error in that setTimeout will be called repeatedly in quick succession, with each one calling view.animate after a 10000 ms delay - the map will become overloaded with animate requests.
Here is a working example using setInterval which ensures that panToNextlocation is called only once per 3000ms
https://stackblitz.com/edit/ol-animation-between-points
I followed the example from the openlayers book to add a static image on top of an osf layer. It works, but my image (256x256) is displayed as a rectangle. I tried around with the coordinates for the projection and checked out other posts here on, but I can't get my head around it why the image is not displayed as a square:
// Create map
var map = new ol.Map({
target: 'map', // The DOM element that will contains the map
renderer: 'canvas', // Force the renderer to be used
layers: [
// Add a new Tile layer getting tiles from OpenStreetMap source
new ol.layer.Tile({
source: new ol.source.OSM()
})
],
// Create a view centered on the specified location and zoom level
view: new ol.View({
center: ol.proj.transform([16.3725, 48.208889], 'EPSG:4326', 'EPSG:3857'),
zoom: 4
})
});
// Create an image layer
var imageLayer = new ol.layer.Image({
opacity: 0.75,
source: new ol.source.ImageStatic({
attributions: [
new ol.Attribution({
html: ''
})
],
url: 'https://placebear.com/256/256',
imageSize: [256, 256],
projection: map.getView().getProjection(),
imageExtent: ol.extent.applyTransform(
[0, 0, 16.3725, 48.208889], ol.proj.getTransform("EPSG:4326", "EPSG:3857"))
})
});
map.addLayer(imageLayer);
ol.source.ImageStatic was made to put a georeferenced image (e.g. a scan of a historic map) on a map. Is this what you have in mind? If you just want to display an image and anchor it to a location on the map, you'd better use ol.Overlay or an ol.layer.Vector with a feature with an ol.style.Icon.
That said, your image will only be displayed as square if the imageExtent set on your ol.source.ImageStatic results in a square on the projected map view.
I don't want that the users see the blank field when dragging the map. I want restrict it. I didn't find any great resolution.
my map code:
var map = new ol.Map({
layers: [new ol.layer.Tile({
source: new ol.source.MapQuest({ layer: 'osm' }) }), vectorLayer],
target: document.getElementById('map'),
controls: ol.control.defaults().extend([
new ol.control.ScaleLine(),
new ol.control.ZoomSlider()
]),
view: new ol.View({
center: [-6217890.205764902, -1910870.6048274133],
zoom: 3,
maxZoom: 20
})
});
Problem:
There are a couple of things that you could do:
Set a background color or image on your map container like in the examples to make the white gaps look nicer.
.map {
...
background: url(map-background.jpg) repeat;
}
Set the minZoom property on the view to prevent the map from being zoomed out too far. But on large screens users might still see gaps.
view: new ol.View({
...
minZoom: 4
})
Or restrict the view extent to the tile boundaries (ol.proj.get('EPSG:3857').getExtent()). This is not yet included in OpenLayers, but you'll find a work-around in this question.
I use the following block of JavaScript to try to show a WMS layer. I'm using OpenLayers 2.8.
The map's base layer (Openstreetmap) shows correctly, it zooms to the correct area, the "pyramid" layer is shown in the layer switcher, but no request to its WMS service is ever made (so the fact that the URL, styles and params are dummies shouldn't matter -- it never even attempts to get them).
OpenLayers does try to get a WMS layer once I pan or zoom far enough so that the Gulf of Guinea is in view (but all my data is in the Netherlands). This suggests a projection problem (WGS84's (0, 0) point is there), but I don't understand why OpenLayers doesn't even try to fetch a map layer elsewhere. My data is in EPSG:3857 (Web Mercator) projection.
/*global $, OpenLayers */
(function () {
"use strict";
$(function () {
$(".map").each(function () {
var div = $(this);
var data_bounds = div.attr("data-bounds");
console.log("data_bounds: " + data_bounds);
if (data_bounds !== "") {
var map = new OpenLayers.Map(div.attr("id"), {
projection: "EPSG:3857"});
var extent = JSON.parse(data_bounds);
var bounds = new OpenLayers.Bounds(
extent.minx, extent.miny,
extent.maxx, extent.maxy);
map.addLayer(
new OpenLayers.Layer.OSM(
"OpenStreetMap NL",
"http://tile.openstreetmap.nl/tiles/${z}/${x}/${y}.png",
{buffer: 0}));
map.addLayer(
new OpenLayers.Layer.WMS(
"pyramid", "http://rasterserver.local:5000/wms", {
layers: "test",
styles: "test"
}, {
singleTile: true,
isBaseLayer: false,
displayInLayerSwitcher: true,
units: 'm'
}));
map.addControl(new OpenLayers.Control.LayerSwitcher());
map.zoomToExtent(bounds);
}
});
});
})();
Edit: the 'data_bounds' console print prints (with some added formatting):
data_bounds: {
"minx": 582918.5701295201,
"miny": 6923595.841021758,
"maxx": 821926.9006116659,
"maxy": 7079960.166533174
}
It zooms to the correct region in the north of the Netherlands, so I don't think the problem is there.
Since posting, I found out that if I don't use the OSM layer, and instead use the WMS layer as baselayer, it works. So perhaps there's some incompatibility with a OSM baselayer and a WMS layer added to it? But then I don't get that it does seem to do something near WGS84 (0, 0).
I eventually managed to fix this by giving the map an explicit maxExtent:
var extent = JSON.parse(data_bounds);
var bounds = new OpenLayers.Bounds(
extent.minx, extent.miny,
extent.maxx, extent.maxy);
var map = new OpenLayers.Map(div.attr("id"), {
projection: "EPSG:3857",
maxExtent: bounds
});
Oddly enough this doesn't limit the user's ability to pan and zoom around the world, but it does make the overlay work...
I've been at this all day long and honestly I'm out of ideas. I have some WMS layers that I would like to display/not display depending on the current zoom level. Yes, I have went through the API docs and they seem to be clear as day, but I follow everything that is suggested and I'm not getting the results desired :(
This was one of the sources that I looked at:
http://trac.osgeo.org/openlayers/wiki/SettingZoomLevels
Then to make matters even worse I found out that if you have an Open Street Map base layer displaying on load it seems to limit your control over the map's numZoomLevels, just what I needed, since I DO want to use this as my loading base layer...
So my questions are:
What am I doing wrong?
Is it true that there really is no workaround on the control of zoom levels when using an Open Street Map base layer on load? Or is there something I just don't know?
Here are some of my code attempts:
Take 1: tib_villages layer should only show when the zoom level is 8-10, doesn't work!
var options = {
controls: [new OpenLayers.Control.Navigation()], //Needed to use GeoExt controls such as the zoomslider
maxExtent: new OpenLayers.Bounds(-20037508.34, -20037508.34, 20037508.34, 20037508.34),
units: 'm',
numZoomLevels: null, //setting the map's zoom levels to null
allOverlays: false
}
var osm = new OpenLayers.Layer.OSM(); //MY base layer
//MY overlay layer
var tib_villages = new OpenLayers.Layer.WMS(
"Villages", "http://localhost:8080/geoserver/wms", {layers: 'cite:tib_villages', transparent: true, numZoomLevels: 10, minZoomLevel: 8}, {isBaseLayer: false, displayInLayerSwitcher: true, visibility: true}
);
Take 2: tib_villages layer should only show when the zoom level is 8-10, map should only have 10 zoom levels, but instead has 19 as the Open Street Map Layer enforces it to, doesn't work!
var options = {
controls: [new OpenLayers.Control.Navigation()], //Needed to use GeoExt controls such as the zoomslider
maxExtent: new OpenLayers.Bounds(-20037508.34, -20037508.34, 20037508.34, 20037508.34),
units: 'm',
numZoomLevels: 10, //setting the map's zoom levels to 10 only
allOverlays: false
}
var osm = new OpenLayers.Layer.OSM(); //MY base layer
//MY overlay layer
var tib_villages = new OpenLayers.Layer.WMS(
"Villages", "http://localhost:8080/geoserver/wms", {layers: 'cite:tib_villages', transparent: true, numZoomLevels: null, minZoomLevel: 8}, {isBaseLayer: false, displayInLayerSwitcher: true, visibility: true}
)
;
Take 3: After getting rid of the Open Street Map base layer on load, the map only has 10 zoom levels as specified, but tib_villages layer should only show when the zoom level is 8-10, doesn't work!
var options = {
controls: [new OpenLayers.Control.Navigation()], //Needed to use GeoExt controls such as the zoomslider
maxExtent: new OpenLayers.Bounds(-20037508.34, -20037508.34, 20037508.34, 20037508.34),
units: 'm',
numZoomLevels: 10, //setting the map's zoom levels to 10
allOverlays: false
}
//MY overlay layer
var tib_villages = new OpenLayers.Layer.WMS(
"Villages", "http://localhost:8080/geoserver/wms", {layers: 'cite:tib_villages', transparent: true, numZoomLevels: 10, minZoomLevel: 8}, {isBaseLayer: false, displayInLayerSwitcher: true, visibility: true}
);
All of your suggestions are sincerely appreciated!
elshae
Try to use minResolution and maxResolution instead of minZoomLevel. It usually works fine. You can get resolution for any zoom lever if you call map.getResolution() method.
Another option is to listen to OpenLayers.Map's zoomend event and toggle layer visibility accordingly. Something like this:
map.events.on({ "zoomend": function (e) {
if (this.getZoom() > 2) {
layer1.setVisibility(false);
layer2.setVisibility(true);
}
else {
layer2.setVisibility(false);
layer1.setVisibility(true);
}
}
});
I would recommend using the maxScale and minScale on the layers instead of resolution, but that maybe is a question of taste. :-) I can't relate to a resolution value, but a scale is easy to understand and to maintain in the longer run, when others look at your code.