Presently I am having problems obtaining elevation point data from the SRTM3 format (.hgt) from NASA. I wish to use the data for creating a program that creates a 2d panoramic illustration of the given area based on the elevation points extracted.
I've exhausted a lot of resources from the Net but still to no avail.
What I want to ask is a form of pseudocode for me to be able to read .hgt files and obtain data from them so I can feed something to my program.
Thanks a lot!
You Could use UniboGeoTools a very small java library that provides Elevation Info in two way: SRTM and Google Elevation Api.
Take a look at the test to understand how it works ..
a pseudocode is:
file a = '~/S41W072.hgt'
size = 1201*1201
for(int i=0;i<size;i++){
int bb= a.readByte();
printScreen(bb,i%1201,(1201-(int)(-1+i/1201)));
}
I have java code somewhere, if I find it I'll upload
Related
I am trying to render a local elevation data on World Wind. And then use the world wind's tessellation algorithm to tessellate the data and render it on the globe.
I know about the LocalElevationModel. and I was able to store a DEM file using this:
LocalElevationModel localElevationModel = new LocalElevationModel();
String filepath = "";
localElevationModel.addElevations(filepath);
I can access this model using the lookupElevation method over the max,min lat log from the localElevation data. But I don't know how to proceed forward. I have looked into the RectangularTessellator class but couldn't understand how to use it.
Any clues on how I can do this?
PS:I was looking at their source code but couldn't understand much to make much scene out of it. So I wanted to know more about it.
PPS: If not possible can someone guide me to an easy to implement and optimized algorithm for rendering of the terrain. Which supports various LODs of the generated mess.
Thanks,
I am working on reverse engineering and i wanted to give my own file path without using open dialog box like writing a fixed file path and read a file from that every time the software start.i tried to give the file name in a .data section of the software but it retrieve only the hex number not the string.
Is there any way hooking windows API for file open?or any way to write in memory and to read it every time the software starts?Any advice or direction would be greatly appreciated.
I think that what you may be looking for is "intercepting system call", quick google search came up with this link:
http://jbremer.org/intercepting-system-calls-on-x86_64-windows/ so it should be possible and not too difficult.
Basically if you manage to intercept a call to GetOpenFileName and replace it with custom implementation you should be able to do what you want (that is put hardcoded file path to appropriate buffer in LPOPENFILENAME structure)
As for your attempt to modify compiled code (I assume that what you are referring as reverse engineering is disassembling and modifying binaries) it should be possible to do, but it will require deep knowledge of windows binary architecture and assembly language.
In my web application I am going to use OpenLayers.Strategy.AnimatedCluster strategy due to the fact that I need to visualize a great amount of point features. Here is a very good example of what it looks like. In both examples in above mentioned example the data (point features) are generated of taken from the GeoJSON file.
So, can anybody provide me with a file containing 100 000+ (better is even 500 000+) features (world cities, for instance), or explain how I can generate them so that they will be located all over the world (not like in Spain in the first example in above mentioned link).
use a geolocation database to supply you the data you need. GeoLite, for example
If 400K+ locations is ok, use download their CSV CITY LIST
If you want more, then you might want to give the Nominatim downloads, but they are quite bulky (more than 25GB) and parsing data is not as simple as a csv file.
I am new to programming. Now i have been learning for a few weeks and am now making my first app. Probably not for public, just for me. At least for now. So here it goes. I want the user to be able to enter his information (for example weight or something like that) into textField and then save it, so I can later form a graph (for example of weight loss through time). Now the graph should not be that much of a problem, since there are many tutorials on that. I am more interested in how to enter information, then save it so it can be later accessed. Any help? What should I read?
Thanks!
Working with UITextFields in Objective C is pretty straightforward - you can grab the NSString from such an object using the 'text' property. Use plists for storage locally, or JSON.
Look at core data tutorials especially related to Apples' doc on “Core Data and Cocoa Bindings”
CoreData shows how to setup objects and save them to a file or simple database. Cocoa Bindings are how to make input screens pass data to object models.
You should be able to write a program to enter weights, save them and show in a table without writing any code.
I am new on this, and my objection is to build some web application that implement the user to store an image on a database as a storage, and all I want is to reduce if there is a couple or some image that stored twice or more.
So, all I need is how to find duplicate or similar images that already stored on a database, or even better when the user try to import it on the first step, and if their image are similar with an images that already been stored on a database, the system can gave a warn not to store that image.
I just want to develop how to find some similar or duplicate image on a specific directory on a database. Can you give me some explanation from the first about how to build it, and what should I learn to accomplished this from the basic step, like a tutorial or something. I'd like to learn a lot, if it's possible.
Thanks in advance, I really need this help, thanks.
The solution for finding similar images is much more complex so I will stick to the finding duplicate images first. The easiest thing to do is to take a SHA1 hash of image bits. Here is some code in C# to accomplish this (see below). As for storing the hash in a database, I would recommend that you use a binary(20) datatype to store the results of the hash. This allows your SQL server to index and query much faster than storing this hash as a string or some other format.
private static byte[] GetHashCodeForFile(string file)
{
int maxNumberOfBytesToUse = 3840000;
using (Stream sr = File.OpenRead(file))
{
byte[] buffer = (sr.Length > maxNumberOfBytesToUse) ? new byte[maxNumberOfBytesToUse]: new byte[sr.Length];
int bytesToReadIn = (sr.Length < maxNumberOfBytesToUse) ? (int)sr.Length : maxNumberOfBytesToUse;
sr.Read(buffer, 0, bytesToReadIn);
System.Security.Cryptography.HashAlgorithm hasher = System.Security.Cryptography.SHA1.Create();
byte[] hashCode = hasher.ComputeHash(buffer);
return hashCode;
}
}
Searching for similar images is a difficult problem currently undergoing much research. And it kind of depends on how you define similar. Some prominent methods for finding similar images are:
Check the metadata (EXIF or similar) tags in the image file for creation date, similar images can be taken at times that are similar to each other. This may not be the best thing for what you want.
Calculate the relative historgram of both images and compare them for deltas in each color channel. This has the benefit of allowing an SQL query to be written and is invariant to image size. An image that has been converted to a thumbnail will be found with this method.
Performing an image subtraction between two images and seeing how close the image gets to pure black (all zeros). I don't know of a method to do this with a TSQL query and this code can get tricky with images that need to be resized.
Calculating the contours of the image (through Sobel, canny or other edge detectors) then subtract the two images to see how many of their contours overlap. Again I don't think this can be handled in SQL.