I use a library that gives me at the end the vtkpoints. Now I would like to extract points
from them. But all the method available from VTKPoints require point id, which i do not know.
Is there a way of doing it?
I can't offer a definitive answer, since the VTKPoints documentation doesn't discuss the values of the point ids and I don't have any experience with this. However, all of the examples I have seen just use integers in the range [0..NumberOfPoints-1] as the point ids, so it would seem that what you are doing is perfectly reasonable (note, however, that your comment I am using the indexes: 0..NumberOfPoints should be 0..NumberOfPoints-1).
The points are definitely just stored in a vector-like container with sequential indexing from 0 to GetNumberOfPoints()-1.
Related
Is there a simple/quick way to find out the dimensions of a 3D axis aligned bounding box for an item with rotations in the <x,y,z> axes? I know that in math there are different methods/equations to come up with the same answer for a problem and I've previously in the past explained with bare bones information about a method that worked for me, that I probably didn't explain well.
I also know that there are (downloadable)functions available for some languages like java and python to help solve/tackle parts of the math. Though that might not help those that want to understand those different methods better or might not have access to those particular functions for the language they are using.
So if a person has the following information:
The item center point coordinate in the x,y,z
The item x,y,z size
Along with the x,y,z rotation(s)
What would be the easiest approach with a person knowing that information, while either using or not using the item center point, matrix/matrices or cos and sin. Though an approach that would also be compact enough to take up the least amount of memory usage.
SITUATION
I have a database with 2,000,000 cities. All of them have coordinates of the city center and mostly all - GeoJSON boundaries. I'm trying to implement a geocoding service that would find cities that intersect with a given point using node.js, mongodb, redis, memcached (and golang, if that is necessary, cause I'm just totally new to it )
PROBLEM
I know how to work with points (lat and lng) since both MongoDB and Redis support geoindexes but I've never seen anything about polygons.
I guess MongoDB won't really help cause of its speed (since it work on disks), but any memory database should deal with this problem. The thing is I can't even think of any way to implement it.
I'll be happy if someone point me how to make it. Thanks.
You may implement a point-in-polygon algorithm yourself. I've done something similar on https://api.3geonames.org
First do a bounding box to identify candidate polygons, then run a PIP. https://en.wikipedia.org/wiki/Point_in_polygon
geo.lua (https://github.com/RedisLabs/geo.lua) works with the requirements you have here but it's not very performant (not sure what has changed since last i checked).
I'm looking for a solution to a Close-Enough Traveling Salesman Problem (CETSP) where I have a set of nodes that I need to visit all within a certain distance of optimally. I've found a couple of sources for some approaches towards this TSP variant but was unable to find a solver or a algorithm that I could easily use.
Do you have any suggestions for how I can go about getting a solution to my CETSP problem, whether it be running an implementation of it myself or using an existing solver.
You can try using UFFLP. They have an example where you can find the correct coordinates the salesman is supposed to pass given a predetermined sequence. So you can generate thousands of sequences and choose the best one (just a simple heuristic).
Have a look at http://www.gapso.com.br/en/ufflp-en/
You will find useful information.
I have a dataset (i.e. a shapefile) containing spatial location data (coordinates) and elevation data as well as other attribute fields.
I want to select points which have at least 200m vertical separation (i.e. are at least 200m apart on the z-axis) AND are within 3km of each other.
The aim is to create a new shapefile with all points that have this relationship with 1 or more other points.
Im sure there is a solution to this problem (maybe not using arcmap at all?) but i just cant find it. any help would be greatly appreciated.
Chris
You are going to have much better luck asking this question in gis.stackexchange.com. Many more ESRI users/programmers there. As a matter of fact I bet you find your solution there without having to ask the question.
You can run the ArcGIS Near tool on all the points.
Then select by attribute points with Z values of >200m and distance values of <3000m.
Help me to learn correlation function in Opencv.
I have read some references but I unable to get a correct idea.
Using Correlation can I match two images and assign weights on them by considering relation between original and another. ?
(becouse I want to match 2 images like same but not 100% same)
Is a kind of Template matching ...?
I wonder if someone can point me a sample code in c++ somewhere in net.
Thank you
You can use Image Correlation to find subimages inside an image.
This is how it works, looking for zeroes inside a textbox:
Also, take a look at this answer