I'm new to qgis and am learning how to download basemaps from various sources. I've been working on a fairly simple map using aerial imagery downloaded from the USGS National Map. Whenever I import the map into my qgis project, the map comes in crooked. Instead of normal north/south orientation, the maps are rotated (approximately 45 degrees) counterclockwise. Is this a projection problem, or am I doing something else wrong. Also, is there a way to correct that within qgis (rotate axis to true north/south).
In similar situations I've found that the projection of the layers didn't match. Something to check
Related
I'm learning QGIS, having moved over from the old OziExplorer. I'm pretty sure my issue is to do with 2 different CRS's. I'm trying to create a map with:
OpenStreetMap or OpenCycleMap (EPSG:3857, WGS 84 / Pseudo-Mercator)
A grid (and POIs) in UTM (EPSG: 32755, UTM Zone 55S)
It shows up as:
Is there a set of steps to do so the Grid is not slightly rotated...or should I just live with it? UTM is great as we are metric and a grid like this is in Metres (1km here). Thanks.
I've pulled up a 'plot of land' raster and I'm attempting to georeference it to Openstreetmap. I can get the raster and the OSM to line up however it isn't accurate enough - there are straight lines that have warped.
I'm assuming this is an issue relating to the message, "Used a ballpark transform epsg:27700 to EPSG:3857" that I get when I add OSM as a layer to a new project set to EPSG27700.
As you may easily tell, I'm quite a novice at QGIS!
I'm trying out Mapbox for the first time, and playing around with drawing some polygons in the dataset editor for export to a tileset. However, the polygons in the resulting tileset are not the same as what I create in the editor. The polygons are only very rough, simplified approximations of the originals.
In dataset editor:
In map layer as tileset export:
I understand that Mapbox does vector simplification at certain zoom levels, but these changes are not zoom-dependent. I zoom in all the way and the shapes are still like this.
Moreover, such extreme degredation of the geometries makes tilesets essentially useless for features that require any sort of accuracy, like property lot lines.
Am I missing something, or is this really the expected behavior? Is there really no way to get accurate geometries into a tileset?
UPDATE: It appears this is only happening with shapes I create by drawing in the Mapbox data editor. So far the geometries that I've uploaded as geojson files have gotten converted to tilesets accurately...
I suspect this is because the maxzoom is too low.
When you create a Mapbox Tileset, either by uploading GeoJSON directly as a new Tileset, or by exporting your your Dataset to a Tileset, Mapbox will try to guess an appropriate minzoom and maxzoom of the Tileset.
Sometimes the min/max zoom's used aren't suitable for the map you're trying to create. Since there is no way to specify a maxzoom in either of the two approaches the only alternative is to create your Tileset locally with https://github.com/mapbox/tippecanoe specifying an appropriate maxzoom for your data and then uploading the resulting .mbtiles as a Mapbox Tileset.
I'm trying to use a Mapbox style in my map. The style loads fine, but it seems to be way off. My GeoJson file should load points in California, and it works fine with other tilesets, but using the Mapbox dataset it loads somewhere north of Canada in the arctic circle. This seems like it's probably a problem with projections. The GeoJson file is in WGS84, which I believe is the Geojson default. The setview centers the view on the US using other tilesets but also centers the data north of Canada using Mapbox data. Here's the bit where I include the Mapbox data
L.mapbox.accessToken = 'correct token';
var map = L.mapbox.map('map')
.setView([43.64701, -79.39425], 4);
L.mapbox.styleLayer('mapbox://styles/mapbox/light-v9').addTo(map);
Leaflet uses LatLng rather than mapbox's LngLat. Do you want your data to be around [43.64701, -79.39425], or around [-79.39425, 43.64701]?
See also Tom MacWright's explanation on why some libraries/formats use lat-lng and some use lng-lat.
I am using TileStache to render a vector tile layer, works nicely in OpenLayers 3.
http://standup.csc.kth.se/maps/projects.html
However, I would like to add "text path" along the roads (e.g. show the year of expected completion). I could not find any way to do textpath in OpenLayers 3. I only found one for OpenLayers2...
I looked at Leaflet for the this purpose but... it does not work with vector tiles, except with plugins that don't seem to allow a combination with the Leaflet textpath plugin...
Is there any solution for doing textpath with vector tiles ?
Text paths along lines are not yet supported in OpenLayers 3, but are a planned feature that should be available later this year.
In the meantime, you could calculate label points and angles on the server and add those to your vector tiles. Then you can style them with a simple ol.style.Text and the rotation option.