Unfortunatly I am new to programming issues and need a clarification regarding panoramio APIs. I have the following generic link:
http://www.panoramio.com/map/get_panoramas.php?set=7000000&from=0&to=10&minx=-180&miny=-90&maxx=180&maxy=90&size=mini_square
This basically allows me to obtain set of metadata in txt-format related to images appearing in this specific Panoramio bounding box.
QUESTION:
Obviously I require a specifc bounding box with different minx, miny and maxx and maxy values. Although changing this values does not provide any different result. Can somebody tell me a way through it or make a short example?
thanks for any explaination,
Daniel, Italy
Your request looks malformed.
if you read the documentation in http://www.panoramio.com/api/data/api.html you see that accepted values for "set" are:
public (popular photos)
full (all photos)
user ID number
So at least you have to change the "set" value to one accepted.
Then add the coordinates of the lower left and upper right corner of your bounding box following carefully the guidelines in the above mentioned web page:
"the minx, miny, maxx, maxy define the area to show photos from (minimum longitude, latitude, maximum longitude and latitude, respectively)."
Related
The traffic incidents needs the boundingBox param (https://developer.mapquest.com/documentation/traffic-api/incidents/get/) and it docs use a location that is geocoded, I would assume to get the boundingBox info but the geocodding api doesn't return anything for it (https://developer.mapquest.com/documentation/geocoding-api/address/get/). How can I get and/or calculate the bounding box? It seems to be related to the lat/lang but it's not obvious.
A default bounding box can be built around a geocode result by adding/subtracting generous values around the returned lat/lng. But usually the bounding box is a result of a user looking at a map and grabbing the bounds of that map.
I programatically create requests to dev.virtualearth.net (Bing static maps).
I know the following values:
Center Point (Latitude & Longitude)
Zoom Level
Map Size (X pixels, Y pixels)
After I recieved the map as a bitmap, how do I determine the Coordinates (Latitude and Longitude) of the upper left corner (basically the very first pixel) and the lower right corner (the very last pixel)?
I just need some suggestions or some pseudo code. Note, that while I know the Center Point, Zoom Level and Map Size, these aren't the same for every request.
Thank you.
You will need to do tile math: https://msdn.microsoft.com/en-us/library/bb259689.aspx
You will need to do the following:
Pass the center point into LatLongToPixelXY method to get the center global pixel value.
Knowing the pixel dimensions of the static image you created, subtract half the width from the x value of the center global pixel value. Do the same with the height and y.
This gives you a new pixel value, pass it into the PixelXYToLatLong to get the coordinate for the top left corner.
That's it :)
I have an old code sample that does this, but retrieves the static image using the old SOAP services rather than the REST services. You can find the blog post here: https://rbrundritt.wordpress.com/2008/10/25/ve-imagery-service-and-custom-icons/ See the LatLongToPixel function code that is half way down the post. That does the above three steps.
I have a question about the use of postgreSQL/postGIS.
I would like to display markers on a map (stored in a database) which are some distance away from the user (coordinates given to the request).
The type of the field of the markers is POINT (I store lat/long).
The user position is detetermined by the Google Map API.
Here is the actual request :
SELECT * FROM geo_points WHERE ST_distance(ST_SetSRID(geo_points.coords::geometry,4326),ST_GeomFromEWKT('SRID=4326;POINT(45.0653944 4.859764599999996)')) > 65
I know (after some research on internet) that the function ST_distance gives me the distance in degree between markers and the user position and that I test the distance in km.
I think I have to use the function ST_tranform to transform the points in metric coordinates.
So my questions are :
- what is the SRID for France
- how can I make this dynamically for the entire world according to the user position ?
I also kow that the function ST_within exists and that could do this. But I anticipate the fact that later, I could need the distance.
Any help would be greatly appreciated
ps: there are maybe solutions in other post, but all the answers I have found during my researches were not really meeting my needs.
Firstly, pay attention to the axis order of coordinates used by PostGIS, it should be long/lat. Currently you are searching in Somalia. Swapping to the coordinates, you would be searching in France.
You can use a geodesic calculation with the geography type, or use geodesic functions like ST_Distance_Spheroid. With the geography type, you may want to use ST_DWithin for higher performance.
Here are geo_points 65 m away or less from the point of interest in France (not Somalia):
SELECT * FROM geo_points
WHERE ST_Distance_Spheroid(
ST_Transform(geo_points.coords::geometry, 4326),
ST_SetSRID(ST_MakePoint(4.859764599999996, 45.0653944), 4326),
'SPHEROID["WGS 84",6378137,298.257223563]') < 65.0;
However, it will be very slow, since it needs to find the distance to every geo_points, so only do this if you don't care about performance and have less than a few thousand points.
If you change and transform geo_points.coords to store lon/lat (WGS84) as a geography type:
SELECT * FROM geo_points
WHERE ST_DWithin(
geo_points::geography,
ST_SetSRID(ST_MakePoint(4.859764599999996, 45.0653944), 4326)::geography,
65.0);
I'm currently working on a mapping app for iPhone. I've created some custom maps of various sizes, but I've run into an issue:
I would like to implement the ability for users' locations to be checked automatically, but since Im not using a MapView this is much more dificult. (see below)
given the different coordinate systems, I would like to receive a geolocation (green dot) and translate it into a pixel location on a custom map.
Ive got the geolocations for the 4 corners, but the rect is askew. Ive calculated the angle of rotation, but Im just generally confused.
note: the size of the maps arent big enough for the spherical nature of the earth to come into calculation.
Any help is appreciated!
To convert a geolocation to point you need to first understand the mapping. assuming you are using Mercator.
x = R*long
y = R*(1+sin(lat))/cos(lat)
where lat and long are in radians.R is radius of earth. the scale of the image would be from 0 to R*PI
so to get it within view.frame.size you may have to divide by a scale factor.
for difference between points.
x2-x1 = R* (long2-long1)
y2-y1 = R* ( (1+sin(lat2))/cos(lat2) - (1+sin(lat1))/cos(lat1) )
I'm familiar with using Google Maps Javascript API. Recently I started using MapKit framework for an iphone project, but I'm having a hard time to figure out zooming and setting a region on map.
In Google Maps API I used to use integer zoom levels like 8, 9, 10 along with straightforward function setZoom(). The only equivalent method I can see in the MapKit framework is setRegion:animated. As I understand, I need to set a region's span's latitude and longitude "delta" values to specify zoom level. But I really don't have an idea what these values represent(I read the documentation).
When I use a MKMapView delegate and trace the span values in regionDidChange delegate method results don't seem to correlate each other. It's ok when I zoom out and see the span delta values are increasing as specified in documentation. But suddenly I drag the map without zooming and delta values become 0.0.
Can somebody please explain what is the reference point to these span and delta? Or is there any algorithm to convert an integer zoom level(like 9) to these delta values?
As a bonus question is there any way to specify a minimum-maximum zoom level on a MKMapView :)
Thanks
First of all, MKMapView does not use/have a predefined set of zoom levels like Google Maps does.
Instead, the visible area of a MKMapView is described using MKCoordinateRegion, which consists of two values:
center (the center point of the region), and
span (the size of the visible area around center).
The center point should be obvious (it's the center point of the region.)
However, span (which is a MKCoordinateSpan) consists of:
latitudeDelta (the vertical distance represented by the region), and
longitudeDelta (the horizontal distance represented by the region).
A brief example. Here's a toy MKCoordinateRegion:
center:
latitude: 0
longitude: 0
span:
latitudeDelta: 8
longitudeDelta: 6
The region could be described using its min and max coordinates as follows:
min coordinate (lower left-hand point):
latitude: -4
longitude: -3
max coordinate (upper right-hand point):
latitude: 4
longitude: 3
So, you can specify zoom levels around a center point by using an appropriately sized MKCoordinateSpan. As an approximation of Google's numeric zoom levels, you could reverse engineer the span sizes that Google uses for a given zoom level and create a span, accordingly. (Google describes their view regions in the same way that MKMapView does, as a center + span, so you can pull these values out of Google Maps.)
As for restricting the region, you may play w/ this delegate method:
mapView:regionWillChangeAnimated
e.g. by resizing the region back into your allowed zoom levels. (Kind of like how table views will let you scroll past the edge, but will then rubber band back into place.) However, your mileage may vary, since I haven't used it for this purpose.
btw, there are definite fixes/improvements in OS 3.1 to aspects of MapKit that were giving me trouble in 3.0.
If you prefer using explicit zoom levels instead of defining an MKCoordinateSpan, I wrote a category that adds support for specifying the zoom level of an MKMapView. The code can be found here.
The span is in degrees of latitude and longitude. There is a method for constructing MKCoordinateRegion structs that takes distance, instead. It may be that you are using MKCoordinateRegionMakeWithDistance to specify the span, and then when you check it in regionDidChange, you're seeing at the lat/long span, which is how it is stored in an MKCoordinateRegion struct.
As far as I know, the integer zoom levels are not available or useful at all when working with MKMapKit. I personally prefer using the span figures, its more flexible.
You cannot specify max and min zoom, and I don't know of a way to hack it in. MKMapKit is actually pretty weak right now, I'm pretty disappointed by the lack of features.
A quick comparison of zoom levels for a location using maps.google.com by inspecting the link querystring shows that the dx and dy span values increase by a factor of 2:
(0.005334, 0.011834) starting span
(0.010668, 0.023668) dx: x2, dy: x2
(0.021335, 0.047337) dx: x2, dy: x2
(0.042671, 0.094671) dx: x2, dy: x2
...
Brant's category on MKMapView works well. However, it appears that it has not been updated to support newer devices with retina screens when calculating mapSizeInPixels.
It can be fixed by replacing this line:
CGSize mapSizeInPixels = mapView.bounds.size;
With this line:
CGSize mapSizeInPixels = CGSizeMake(mapView.bounds.size.width * [UIScreen mainScreen].scale, mapView.bounds.size.height * [UIScreen mainScreen].scale);