I'm displaying a map that's been tiled (-p raster) using gdal2tiles.py. The X-coordinate is about [0..-1160]. The Y-coordinate, for some reason, is [-700,0]. Zoom-levels 0-5.
I simply cannot get a plausible display to work. Sometimes, if I zoom-out to level-zero, I see the map way down at the bottom of the display ... not centered. Nothing at all appears at other levels.
I am also seeing the display "bounce back and forth" between about a 3-o'clock and a 6-o'clock position. (Only, once again, at zoom-level zero.)
I am at my wit's end. Please give guidance. Complete examples. Anything ...
Well, I found my answer:
If you're going to be using several layers in your Leaflet map, add them in the constructor-call, using the layers parameter.
If you try to do things with the layers before joining them all together, or with the map with no layers added, "strange and default things will happen." (For example, although I requested the Simple CRS when constructing things (separately...), the net-effect was to actually try to use a different one. Therefore, "do what the author expected." Specify all the layers at once, to the Map constructor. Then, customize them as you need to. Make very sure that they all know about each other from the very start of things.
Related
Let's say I have a container. I want to surround it with a border (or anything that would outline it) and be able to change it's start and end points. This would be similar to the trim paths effect in Adobe After effects. I've looked up options for container borders but the best I could find was to add it to juts one side and that is not the look I want.
The best way I can describe what I want to do is to have a border or outline to the container that looks sort of like a circular progress (but isn't round and takes the shape of the container) that has the start and end points move.
Here is a quick example I made in After Effects of what I am looking for: https://drive.google.com/file/d/1DgHZbLv_TX1D_lpfYJlL4QA0kOVbQZDe/view?usp=sharing
This needs to be done through CustomPainters. Here is a repo I came across which does this through custom painters https://github.com/divyanshub024/flutter_path_animation.
I have been rendering a FeatureCollection of polygons into the Map (in one GeoJSONLayer). The size of each polygon is big (5mb, 10mb). With user interactions, the colours of polygons would be re-calculated & changed constantly. We are using data-driven method and keeping the data in properties of each feature. So GeoJSONLayer has to call .setData(geojson) everytime the data and colours changed (they are kept in properties).
I find above approach is lead to performance issue since the size of geojsons is big and calling .setData() is expensive.
I'm thinking of separating the geojson source and the data, style, colouring and calling direct function (setPaintProperty) whenever colours changed would be better than.
Someone told me that .setData and .setPaintProperty would do the same thing, both 2 will trigger re-rendering whole polygons.
Kindly need help to advice on this matter
Thanks a lot!
If I understand you correctly, you're asking which of these two is faster:
map.setData(mylayer, mygeojson)
map.setPaintProperty(mylayer, 'fill-color', ...mydatadrivenproperty)
I haven't tested, but I'd assume the second is faster, because the first one has to:
Parse the GeoJSON
Convert it to vector tiles
Repaint
whereas the second just has to parse the property repaint. Try them both out to see.
You may also consider a third way, which is to have a second layer which is a highlight, which you update by calling map.setFilter(mylayer, ...).
I am loading a bunch of geojson points. I can see that I am loading about 40 points but which ones get displayed on my map seems random and somehow connected to the zoom level. Below you can see that only 2 points of ~40 are displayed.
What criteria does mapbox-gl-js use to decide what to display?
Is there a way to control what points are being displayed? (All of them? Some based on an attribute?)
This is likely occurring because you are using the default text-allow-overlap value of false. The text-allow-overlap documentation reads
If true, the text will be visible even if it collides with other previously drawn symbols.
Because your symbols overlap each other, some are hidden. You can disable this behavior by setting text-allow-overlap to true.
You might find marker clustering to be useful.
Has anyone had issues with Tableau Maps displaying backwards? I believe the only workaround for this would be to have my own custom background image and supply the min/max lat/lon.
My data is outlined as the following, and is plotted using the lat/lon in the data.
City | Latitude_DC | Longitude_DC
The not-so-evident and not-the-best solution that pops to mind is the one provided in the comments, simply dragging/moving the map using the mouse and publishing the dashboard without resetting the axis.
In your dashboard you can even create a small floating text-box alerting people to not pin the map if it's something you might be concerned.
I'm not sure about how Tableau's algorithm works to decide that the best map position for your data is putting the United States at right, and I don't think there's a real fix for that (if it's considered a bug to be fixed).
so i have looked at a couple other questions like this and from what i saw none of the answers seemed to answer my question. I created a program that creates ASCII art, which is basically a picture of text instead of colors. the way i have the program set up at the moment you have to manually set the Width and Height of the pixels. If the width and height of the pixels is too large it simply wont work. so basically what i want to do is have a function to automatically set the width and height to the size of the picture. http://www.mediafire.com/?3nb8jfb8bhj8d is the link to the program now. I looked into pixel grabber but the constructor methods all needed a range of pixels. I also have another folder for the classes, http://www.mediafire.com/?2u7qt21xhbwtp
on another note this program is incredibly inefficient, i know that it is inefficient in the grayscaleValue() method, but i dont know if there is any better way to do this. Any suggestions on this program would be awesome too. Thanks in advance! (this program was all done on eclipse)
After you read the image into your BufferedImage, you can call getWidth() and getHeight() on it to get this information dynamically. See the JavaDocs. Also, Use a constructor for GetPixelColor to create the BufferedImage once and for all. This will avoid reading the entire file from disk for each channel of each pixel.
For further code clean up, change series of if statements to a switch construct, or an index into an array, whichever is more natural. See this for an explanation of the switch construct.
One last comment: anything inside a class that logically represents the state of an object should be declared non static. If, say, you wanted to render two images side by side, you would need to create to instances if GetPixelColor, and each one should have its own height and width attributes. Since they're currently declared static, each instance would be sharing the same data, which is clearly not desireable behavior.