I followed this example : http://bost.ocks.org/mike/map/
to display this topojson file :
https://github.com/max-l/topojson-experiments/blob/master/qc-map.json
the map is always empty, I tried setting the proper center
d3.geo.albers().center(-71,45) and many other things without success.
I noticed that Github is able to render it (with leaflet)
https://github.com/max-l/topojson-experiments/blob/master/qc-map.json
which makes me assume it is valid topojson..
I'd guess its a projection issue. The co-ordinates in the topojson and your center look like they are WSG84 or Mercator co-ordinates (the America's are expressed as negative longitudes) and they are similar to the coordinates in this question. WSG84 is generally a safe guess for projections particularity for things like Google Maps, although Albers is commonly used for North America.
I've made a gist using Mercator which displays the map and you can see the block here.
Related
In Kibana we have a visualization called Tile map which has has several options to customize, such as map type.
My question is about one of this types: Shaded Circle Markers which is basically about changing colors based on value.
Documentation says:
Displays the markers with different shades based on the metric aggregation’s value.
and that's correct, but I don't understand why some bubbles are bigger than others.
I assume that this may be due to the distortion caused by Mercator projection, which which is well presented by Tissot's indicatrix, but I didn't find any source which confirming my hypothesis.
Could you confirm my suspicion or explain in other way this behavior?
I've got an answer from Elastic Team Member who confirmed my suspiction. This distortion is caused by Mercator projection.
Link to Elastic Search forum: https://discuss.elastic.co/t/size-of-the-circles-in-kibana-tile-map-visualization/108395
Three.js Mirrored Normal Maps Flipped Channel
I'm using 3dsmax 2013 (FBX 2013) with tangents and binormals included. I'm also setting :
Horse_normalMap.wrapS = THREE.MirroredRepeatWrapping;
However it seems that even by flipping the mirrored UVs back to their non-flipped original state (and then flipping them in THREE.JS) it means the red channel is still inverted. I tried to debug the tangents using the TangentsHelper but that seems to have been removed from what I've read. I may have to go back to using unmirrored UVs unless there's a good workaround.
I looked briefly/hopefully into derivative maps as they seemed to offer a wayout from tangent based mismatches; but the few examples all seem to use the same displacement map and not the typical deriv 2-channel maps written about elsewhere. I tried 3 different displacement map generators (HP>LP) and all gave me very noisy results. There doesn't seem to be any docs on what it expects, I did come across an open bug report (sorry not enough rep to post more than 2 links) which suggests this is an open issue still.
Anyone happen to know of an example or can point me in the right direction on rendering a heightmap/terrain in WebGL from a three dimensional array? Basically I have an array that contains data relevant to x and y coordinates and a 'height' (z axis).
Everything I've found (like in the threejs world) shows how to create one dynamically or from a 2d image. Ideally I'd like to have the color of the pixel/particle related to the height. Basically looking to do something like below but in WebGL:
There are many examples on how to do this already available. You can search for three.js + heigthmap.
Or try three.js + 3d graph.
Here is something called a "Graphulus-Function" that looks pretty much exactly like what you need.
Here you can find another interesting reference.
Without more details on your data it is hard to say if these examples suit your needs...
Check also this three.js issue 1003 on GitHub: "Terrain from Heightmap" where there is a discussion about this topic and lots of great examples are mentioned.
I've asked similar questions before and I'm still struggling.
I want to create geo based info graphics at the level of a city.
I need to be able to take some latitude/longitude values and project them such that they are centered and appropriately zoomed.
It would help me a great deal to see an example that plots a small number of points.
37.781040, -122.497681
37.720504, -122.495622
37.723220, -122.395028
This is roughly an L shape and all three points should be in San Francisco.
It could be as simple as 3 black dots on a white background. I hope to learn:
which projection?
how do you adjust the projection so that an area the size of San Francisco is on the canvas?
how do you translate those coordinates and position them on that canvas?
Could someone create such an example?
Thanks.
-Kelly
I created a simple example that works.
https://gist.github.com/kellyfelkins/9741723
I think I was making multiple mistakes that made it really difficult to correct.
In case others have troubles too, here are some things to watch out for:
The projection method expects an array. For a while I was passing it 2 arguments, but it needs a single argument that is an array.
The projection expects the values in longitude, latitude order.
-Kelly
Summary: I need a tool that can put 60m+ points on a map image. I'm trying to show density map and would like to plot a dot for each point (lat/long) on the map.
Hi I'm working on project that requires a density map. I have latitude and longitude and all the tools that I have seen (Ammap, FusionCharts maps, google charts/map) requires either XML or JSON or some other data type with the data points. Problem here is that, I have 60 million + data points and transferring any type of object with that many data point is not feasible.
One solution I can think of is mapping latitude and longitude to pixels of the map image. That requires a lot of time and work. I was wondering if you guys have done something similar and know of tools that can do this for me. It doesn't have to be free.
You'd be much better off creating a heatmap instead of passing all of the individual points to the map, which would get very busy, very quickly.
There are already a few discussions over at GIS.StackExchange about this exact topic. Search the the [heatmap] tag.
Since you mentioned FusionCharts, assuming you can load all of your data into a Google Fusion Table, it looks like you should be able to make a heat map in Google Fusion Tables).