I am using the map service at http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer, which gives me a world map.
I have a shape file (.prj) that looks like this:
PROJCS["UTM:10N",GEOGCS["GCS_North_American_1927",DATUM["D_North_American_1927",SPHEROID["CLARKE 1866",6378206.4,294.9786982]],PRIMEM["GREENWICH",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["Central_Meridian",-123.0],PARAMETER["Latitude_Of_Origin",0.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],UNIT["METER",1.0]]
The locations relevant to the shape file are in western Canada (UTM:10N). Research seems to indicate that this is WKID 26710.
If I create the map layer and set the SpatialReference to 26710, no map shows. If I set SpatialReference to 102100, I get a map, but my points are in eastern France. This tells me that my reference is off.
I am processing the shape files, but I do not create or own them. How would you go about getting them to position themselves correctly in Canada? It seems that the answer would be to "get the right Spatial Reference", but all the searching I have done says that that is 26710.
The map service you're using only plots geometries supplied in the 102100 projection. If you have access to an ArcGIS Geometry server, you can convert your data points from the source projection to the one required by the map service. See http://resources.esri.com/help/9.3/arcgisserver/apis/rest/project.html
For example, if you have a point whose coordinates in the 26710 wkid are (491800, 5456280), you could do something like
http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer/project?inSR=26710&outSR=102100&geometries=%7B%22geometryType%22%3A%22esriGeometryPoint%22%2C%22geometries%22%3A%5B%7B%22x%22%3A491800%2C%22y%22%3A5456280%7D%5D%7D&f=pjson
The x and y coodinates in that result should show up somewhere around Vancouver on the map service you linked.
Related
Is there a way to add error bars to scatter plot data using VTK? I am currently plotting point data using the C++ API; there is uncertainty associated with the data I am trying to plot which I would like to visualise also.
I can't find any obvious references in the documentation to error bars; the only mention I have found is in this Kitware presentation from 2011, which doesn't seem to be a function that exists.
Sample code snippet:
// Chart source data is populated etc...
vtkPlot* sampleScatter = chartXY->AddPlot(vtkChart::POINTS);
sampleScatter->SetInputData(chartDataTable, 0, 1);
// Here is where I would like to add the error bars -
// below method is from the link, and does not work
vtkPlotPoints::SafeDownCast(sampleScatter)->SetErrorArray(errorData.GetPointer());
// Chart is rendered...
where chartXY is a vtkChartXY object and chartDataTable is a vtkTable containing the x and y data in columns 0 and 1.
Is there a way to populate error data for visualisation in a similar fashion to the above, or will I have to roll my own chart type?
It turns out that this is not a capability that exists in VTK at the moment.
I have developed a basic capability to do this, which is currently the subject of a merge request in the VTK repository. Will update if/when this has been merged in and the capability is available.
I modified a mesh, and some edges were added.
Then I saved the modified mesh to a .obj file. When I open this .obj file using OpenMesh read function, the indices of edges are different from the indices of edges when I saved the mesh, because the .obj file only has information about vertices and faces.
I need to save an additional edge information file in the edge index order when saving the modified mesh. But according to what I mentioned above, the order is different, so the edge information is wrong after reopening the modified mesh.
I have a solution. I save the modified mesh(old mesh), then read the saved file as new mesh. Check every edge of the new mesh in index order, and find the same edge in old mesh. Then I can output the edge information in edge index order of new mesh.
Is there a simple solution without reopening? For example, an OpenMesh function that recalculate the edge indices?
Thanks
From what you say I figure that you are probably using (or at least should be using) a custom edge property where you store your additional information. Ideally like so:
auto edge_pm = OpenMesh::makePropertyManagerFromExistingOrNew<
OpenMesh::EPropHandleT<std::string> >(mesh, "edge_info");
// Set some random edge info.
edge_pm[mesh.edge_handle(23)] = "foo";
You could use OpenMesh's native .om format which allows you to store custom properties. Have a look at the unit tests in /src/Unittests/unittests_read_write_OM.cc, specifically the WriteTriangleVertexBoolProperty one which implements an example where a mesh with a custom property is saved to a .om file and then read from that file again. For the example above it would look something like this:
// Flag property so it gets serialized.
mesh.property(edge_pm.getRawProperty()).set_persistent(true);
bool ok = OpenMesh::IO::write_mesh(mesh, "bar.om");
When you load the mesh from file, be sure to first create the property:
Mesh new_mesh;
auto new_edge_pm = OpenMesh::makePropertyManagerFromExistingOrNew<
OpenMesh::EPropHandleT<std::string> >(new_mesh, "edge_info");
bool ok = OpenMesh::IO::read_mesh(new_mesh, "bar.om");
Afterwards your property should be restored:
std::cout << new_edge_pm[new_mesh.edge_handle(23)] << std::endl;
// Should print "foo"
So I'm working on a project for a class and I'm still trying to figure out how to go about doing something.
I am making a game where there is a board of squares or hexagons, they are either black or white, each being a state of being "Flipped", and when you click one square/hexagon, it flips all the adjacent shapes too.
Here is an image of what I am aiming to create.
Assignment images
I have gotten it running with squares, but now I need to do it with Hexagons. With the squares I registered a mouseclick as being within a square parameters of the x and y location of the click, and the state changes are assigned to a list of values assigned similarly to how the shapes were assigned within a list.
I will include a quick recording of the square program running in a folder I'm going to link.
Now, I believe I can't apply this kind of system to hexagons since they don't really line up like the squares did.
So how would I go about making a click register within a single hexagon on a grid? I have already drawn out the grid, but I am stuck on what to do to register a click to allow a hexagon to change it's state from un-flipped to flipped. I'm pretty sure I know what to do for the state change itself, but I don't know how to go about this, would it involve something with making a separate Class or something? I would appreciate any help with this.
I'll put a dropbox link here for the progress I made so far, and a pdf manual for graphics.py.
Dropbox: Python files
You can view the python code in your web-browser with dropbox too, I don't really want to fill this page pull of an entire thing of code..
Any help and feedback would be wonderful, thank you c:
so, TL;DR: How do you register a click within a polygon shape in python that allows it to change a value (within a list?) and change its visual appearance.
Just for the general side of your question, you can use a test to check if a point (x, y) is inside a polygon (formed by a list of x, y pairs).
Here's one such solution: http://www.ariel.com.au/a/python-point-int-poly.html
# determine if a point is inside a given polygon or not
# Polygon is a list of (x,y) pairs.
def point_inside_polygon(x,y,poly):
n = len(poly)
inside =False
p1x,p1y = poly[0]
for i in range(n+1):
p2x,p2y = poly[i % n]
if y > min(p1y,p2y):
if y <= max(p1y,p2y):
if x <= max(p1x,p2x):
if p1y != p2y:
xinters = (y-p1y)*(p2x-p1x)/(p2y-p1y)+p1x
if p1x == p2x or x <= xinters:
inside = not inside
p1x,p1y = p2x,p2y
return inside
This can be used in a way that is quite symmetrical to your drawing code, as you also form polygons in the same way for drawing as you would to test to see if the cursor is inside a hex.
You can modify the above implementation also to work with this Point type you are using to draw the polygons.
The rest you should be able to figure out, especially considering that you managed the input handling and drawing for the square grid.
I've got the BumbleBee 2 stereo camera and two mentioned SDKs.
I've managed to capture a video from it in my program, rectify stereo images and get a disparity map. Next thing I'd like to have is a depth map similar to one, the Kinect gives.
The Triclops' documentation is rather short, it only references functions, without typical workflow description. The workflow is described in examples.
Up to now I've found 2 relevant functions: family of triclopsRCDxxToXYZ() functions and triclopsExtractImage3d() function.
Functions from the first family calculate x, y and z coordinate for a single pixel. Z coordinate perfectly corresponds to the depth in meters. However, to use this function I should create two nested loops, as shown in the stereo3dpoints example. That gives too much overhead, because each call returns two more coordinates.
The second function, triclopsExtractImage3d(), always returns error TriclopsErrorInvalidParameter. The documentation says only that "there is a geometry mismatch between the context and the TriclopsImage3d", which is not clear for me.
Examples of Triclops 3.3.1 SDK do not show how to use it. Google brings example from Triclops SDK 3.2, which is absent in 3.3.1.
I've tried adding lines 253-273 from the link above to current stereo3dpoints - got that error.
Does anyone have an experience with it?
Is it valid to use triclopsExtractImage3d() or is it obsolete?
I also tried plotting values of disparity vs. z, obtained from triclopsRCDxxToXYZ().
The plot shows almost exact inverse proportionality: .
That is z = k / disparity. But k is not constant across the image, it varies from approximately 2.5e-5 to 1.4e-3, that is two orders of magnitude. Therefore, it is incorrect to calculate this value once and use forever.
Maybe it is a bit to late and you figured it out by yourself but:
To use triclopsExtractImage3d you have to create a 3dImage first.
TriclopsImage3d *depthImage;
triclopsCreateImage3d(triclopsContext, &depthImage);
triclopsExtractImage3d(triclopsContext, depthImage);
triclopsDestroyImage3d(&depthImage);
I'm currently using GeoDjango in a "Star searching and sorting" database that provides information about and will simulate information on star and planetary systems.
I'm using GeoDjango 1) because I like it and use it elsewhere, and 2) because I eventually want to use various "geo" searching features like distance/lines/polygon transforms for complex and cool volumetric querying that I can't find elsewhere.
I have the system up and running (https://github.com/jaycrossler/procyon) and it currently uses star Galactic Coordinates (already transformed from Right Ascension/Declination). There are 150k stars currently in the database, and I'm considering increasing to a few million.
After a star is in the database, I build a new table that has a GeoDjango PointField, then populate it with the Galactic X, Y, Z coordinates (which are in parsecs, and such are mostly in the range of -500 to 500). Right now, I've set the SRID to 900913 (so that I'll have a good range of coordinates that won't roll over around the world line)... but when I search on the nearby stars and order by distance, I'm only getting returns that are in a line, rather than being truly near based on X,Y,Z distance.
location = models.PointField(dim=3, blank=True, null=True, srid=900913)
objects = models.GeoManager()
I think this is because every search I make is ultimately getting wrapped onto the surface of a sphere, and that's both inefficient and screwing with results (though if it makes searching only take one line of code, I'm cool with it).
The current searching I'm using in Django is:
origin = self.location
distance = 1000
close_by_stars = StarModel.objects.filter(location__distance_lte=(origin, D(m=distance))).distance(origin).order_by('distance')
for s in close_by_stars[:200]:
#export results
But the results returned are not what I expect (I would think they'd clump around one star, not be in a line), visualized:
So, the big question is:
1) Should I use a SRID such as 900913 (Spherical Mercator)
or
2) Is there a SRID that isn't mapped to the surface of a a planet, so that I can just search on X, Y, Z distances without it rolling over a -180 into a +180 (or whatever equivalent based on projection system)? I tried using SRID=0, but geodjango than pukes and doesn't allow that.
I've got a fix, which I'm sharing here to potentially help others.
I think the issue is that the 'location__distance_lte=' function gets transformed in POSTGIS to the geo function ': ST_DWithin
From looking at pg_log/latest, I see the SQL command:
SELECT (ST_Distance("modelname"."location",
ST_GeomFromEWKB('\x01010000a031bf0d0021e527d53e2963409f3c2cd49ab2404081b22957787d5540'::bytea))) AS "distance",
"modelname"."info", "modelname"."location"
FROM "modelname" WHERE ST_Distance("modelname"."location",
ST_GeomFromEWKB('\x01010000a031bf0d0021e527d53e2963409f3c2cd49ab2404081b22957787d5540'::bytea))
<= 10.0 ORDER BY "distance" ASC
So, when searching by X, Y, Z and looking for the nearest points, it only searches within 2D space - and looks for the ones within X, Y distance... not the ones within Z.
There is an ST_3DDWithin (http://postgis.net/docs/ST_3DDWithin.html) but unfortunately Django doesn't know about it: https://github.com/django/django/blob/master/django/contrib/gis/db/backends/postgis/operations.py#L154.
Instead of overriding the django source I could use the raw sql method: https://docs.djangoproject.com/en/dev/topics/db/sql/#django.db.models.Manager.raw.
But, then the orm would lose a lot of it's benefit.
But instead, I decided to go a bit simpler/more complicated. I kept the same search (which returns basically a "cylinder" instead of a sphere of results). Then, in the function, I loop through the results and parse out the ones that aren't within the spherical results:
origin = item.location
origin_array = numpy.array((origin.x, origin.y, origin.z))
close_by_stars = star_model.objects.filter(location__distance_lte=(origin, D(m=distance))).distance(origin).order_by('distance')
star_list = []
for s in close_by_stars:
location_array = numpy.array((s.location.x, s.location.y, s.location.z))
dist = numpy.linalg.norm(origin_array - location_array)
if dist > distance:
continue
star_handle = dict()
star_handle['data'] = s.data ...