So I've found many jquery simulated zoom tool demonstrations (example) where a small image and large image are stored on the server. When the mouse pans over the small image a mapped portion of the larger image is shown in a zoom window.
The zoom feature I am hoping to employ will be used on a slippy map (openlayers,tilelite,mapnik) so it will be easier for my old eyes to see the street names. So it is not practical to have larger versions of all the image tiles on hand for zooming. Is it possible to actually zoom (as opposed to simulated zoom) over dynamic web page content?
I do realize I can change the font sizes in the mapnik configuration files and I will do that if there are no other options available, but I'd like to avoid that if possible.
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I am using Mapbox GL JS to overlay an image of satellite data over Texas. The image is big enough to cover Texas, but even when using 100% correct geo-coords, the image is not in the correct place. I have to split the image into 6 long (west-east) images like such, and stack them vertically in separate image overlays :
This produces the desired result :
When using the 6 stacked image overlays (each 2 degrees tall and very wide to cover the state's width, by the way), the placement of the clouds is exactly perfect with zero issues. It's perfect except that having to make 6 image overlays to build this is not at all ideal and it adding processing constraints.
If I merge all the images into one big picture and overlay it using the same coords - the effect is wrong. Even though the image is exactly the same. I have highlighted the coastline so you can see that when using one large image overlay for the whole state, it becomes inaccurate. For a storm chaser (my target audience) this would not be unacceptable. I have tried manually adjusting the images but it is no good and I have wasted days of my life tracking this issue down, and it is absolutely Mapbox. I have ruled out the other possibilities like bugs in the software I use to get the data.
Here is the bad result with one overlay as opposed to splitting it vertically :
Are there any ideas to what may be causing this, and a solution? I am completely lost.
I had solved this long ago but since others have the same problem, it deserves an answer here. The problem has to do with projection. Images can be sliced and diced exactly by coordinates but they must match the projection of the map they are being overlaid on. In the case of Mapbox, it uses web mercator and images must be reprojected to EPSG:3857.
A utility to convert images (such as geoTIF) to this projection is GDAL (https://gdal.org/). A command using GDAL tools to convert an image would be something like :
gdalwarp -t_srs EPSG:3857 input.tif input-projected.tif
Hopefully this clears things up. These issues are basic knowledge in the GIS community. If you want to work with data like this, I can say that I recommend doing what I did : learn basic GIS tools and how they work. It will save you.
I can draw custom shapes using polygons in Inkscape. My goal is to display these shapes on top of the map of the US at fixed positions. The map and the polygons will display on a webpage with the ability to zoom in and out and pan. I wanted to know if these polygons can be placed on such a map using OpenLayers. How? Example anywhere? I am not familiar enough with OpenLayers and would learn it more if it can meet my requirements. I need to programmatically be able to color fill each shape either server or client side. I also want to place markers on the map based on lon/lat coordinates. Does OpenLayers support all this?
This is an example of what I want to do. The area in orange was defined in Inkscape and the color orange can be a different color set programmatically. This is a simple svg file displayed on the web page.
You should be able to treat the exported SVG as a regular image overlay. Here is the OpenLayers API for image overlays and here is another SO answer with a very basic image overlay example. OpenLayers supports markers, though if you're embedding the SVG as a flat image, I'm not sure if OpenLayers will allow you to style the SVG elements out of the box...
As an aside, Polymaps is an alternative mapping library that's slightly more SVG-oriented; it's especially good for stuff like dynamically transforming SVG layers based on data, manipulating styles and classes for SVG elements, etc. Per your example, here's their example for very simply throwing an image (with defined top-right / bottom-left coordinates) on a map.
I have a static image, which I wanna be able to zoom into with the Google Maps API. However, I do not have any higher resolution tiles available, so the idea was to simply zoom in the one image and stretch it accordingly. This works fine if I make the getTileURL() function return null, and instead define the image as a GroundOverlay. The problem is, zooming in on images for GroundOverlays has to resize and reposition them, and you can notice that process distinctly. This is an example from the Google Maps Developer's Guide, which has the same problem:
https://google-developers.appspot.com/maps/documentation/javascript/examples/groundoverlay-simple
If you zoom in on the map, you will notice the image appearing again in regular size for a split second, then be stretched and repositioned to fit the coordinates.
Is there a way to disable that entirely? I know it can zoom into images smoothly, because it does that with regular image tiles, it zooms in and the replaces them as soon as the higher resolution tiles have loaded. Is it possible to somehow emulate this effect for GroundOverlays?
Basically what I am trying to do is find a way to load ONLY one image/tile which will fill the viewport and not have any surrounding tiles loaded. It appears this is the methodology the good folks at Weather Underground are doing w/their Wundermap.
I've tried digging through their code but to no avail. I tried simply using larger tiles - larger than the actual viewport - but this has several adverse side effects. There was a similar question asked in WMS as a single tile image in Google Maps v3 but that was more about just using larger tiles than using a single tile.
Thanks in advance.
UPDATE:
Here is a link to a page/map on their site that loads a single tile/image that spans the entire viewport:
http://wxug.us/o4ia
If you have the Net tab open in firebug you can see that there is a single tile request. Also, if you keep it open and pan the map - while keeping the mouse down - the data does not fill in until you release the mouse. For all the tiled maps I have seen, as soon as you pan, it starts filling in new tiles.
They're using a custom overlay. You'll need to set up a server-side way of serving out your own image overlays to display on Google Maps, based on the viewport (presuming you want to serve 1 image that displays over the entire viewport). http://goo.gl/zgEKB
Seatgeek has a zoomable draggable tiled interface.
An example is here:
http://seatgeek.com/sf-bulls-yankees-tickets/3-2-2012-tampa-george-steinbrenner-field/mlb/785875/#
I want to implement a scrollable draggable interface like this but I cannot use Google's code for google maps.
Also I need the tile system like google maps where it pulls tiles from the server for rendering the map.
Need to implement in javascript. What library can I use? How can I do it?
How does seatgeek do it?
I de-compiled their javascript http://pastebin.com/PVjahhnH
Map Client
OpenLayers
OpenLayers Examples
Map Data
OpenStreetMap
This kind of interface seems complex to implement, but it is just some math tricks. If you decide to implement your own algorithm, try this out:
Take the full image and create tiles in different scales and consequently with different depth.
The user start looking at the scene in real scale, composed by 16 tiles created from the original scene.
If the user drags, all tiles moves equaly. If the user zoom in, all tiles are scaled up.
If the user zoom more than X, you change the 16 tiles by their 16 child tiles! Got it? Higher the zoom, higher the detail. To avoid having 36000 tiles at the same time, generate with different depth and switch them on the fly.
You just need to load and move the tiles. Multiply tile x, y, width, height by the zoom. Keep the focus of the scene in the mouse position. Take a look at this example. It does exactly the steps above, but with a lot of microscope images. It is the same idea of google maps.
CloudMade map tile is one of the server based map tile service. Please read this page server http://cloudmade.com/documentation/map-tiles or contact with alex#cloudmade.com for more information.