<div dir="ltr">Hello Remi,<div><br></div><div>Your suggestion with point clouds worked perfectly. </div><div><br></div><div>Thank you!</div><div><br></div><div>Best regards,</div><div>George</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Dec 3, 2014 at 1:21 PM, Rémi Cura <span dir="ltr"><<a href="mailto:remi.cura@gmail.com" target="_blank">remi.cura@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div><div>Hey,<br></div><div>I'm afraid you don't have given the most important information<br>, thus not allowing to choose between a value per row or a file per row!<br><br></div><div>So I discuss both :<br></div><div> first hypothesys : you'll have few files at a time,<br></div><div> - number of values is not very high (few millions)<br></div><div> - you want to get parts of the data based on index (1D,2D,3D) or maybe value<br></div><div>You will store each value of the file into a row.<br></div><div>Thus a file with a char array of size N will yield a table of N rows.<br></div><div>CREATE TABLE one_value_per_row (<br></div><div>gid int, --contains 1,2,..N , ordered by x,y,z<br>X int,<br></div><div>Y int,<br></div><div>Z int,<br></div><div>value smallint --or somehting like that<br></div><div>);<br></div><div> if you want your point ordered with original array index<br>SELECT *<br>FROM one_value_per_row<br></div><div>WHERE gid BETWEEN 2 AND 45; <br></div><div>More interesting, you can select 1-2-3D line/square/cube like this<br>SELECT *<br>FROM one_value_per_row<br>WHERE X BETWEEN 2 AND 3 <br></div><div> AND Y BETWEEN 56 AND 89<br></div><div> AND Z BETWEEN 21 AND 42;<br><br></div><div>of course for this kind of querry to beb efficient, you need some index<br></div><div>CREATE INDEX ON one_value_per_row (gid);--the same for all columns<br></div><div><br></div><div>This approach __won't__ scale<br></div><div><br></div>Second hypothesis : you have a great many of files (over the hundred range)<br></div><div><b>you will store each file in one row.</b><br></div><div>Now you have at least 3 options.<br><div>* You store the data as a postgres type, the simplest is a postgres array<br></div> each row would contain a smallint[] (for instance)<br></div><div> This may not perform well with millions of values<br></div><div> You access your data like you would for a C char[] : value[35%12]<br></div><div> I think it is a pretty bad idea <br></div><div><br></div><div> * You ask the database to store the original binary, and you have to create C/python function in the database to access the data<br></div><div> (like get_values(Xmin=1,XMax=3,YMin=56,YMax=89,Zmin=21,ZMax=42))<br></div><div> this is an approach identical to the <a href="https://github.com/pgpointcloud/pointcloud" target="_blank">pg_pointcloud</a> project<br> For instance, your data could be stored as a 3D numpy array. slicing it would be then efficient and very easy (one line)<br></div><div> <br>* You don't want to redevelop, and use pg_pointcloud out of the box : <br> You consider that each value of your original array is a 3D point<br> Then each file is a point cloud stored on one row of the database.<br> you define each value of your initial array as a point X,Y,Z being the 3D coordinate. you store the value in an attribute, You can also store the original array index<br></div><div> This is the easiest and most efficient out-of-the-box solution <br> (see <a href="http://boundlessgeo.com/wp-content/uploads/2013/10/pgpointcloud-foss4-2013.pdf" target="_blank">this introduction presentation</a> , and <a href="https://github.com/Remi-C/Postgres_Day_2014_10_RemiC/raw/master/presentation/A%20PostgreSQL%20Server%20for%20Point%20Cloud%20Storage%20and%20Processing.pdf" target="_blank">this simple to complex presentation</a> )<br></div> <br></div><div> you would get your data like this<br></div><div> SELECT pc_get(pt,'X'),pc_get(pt,'Y'),pc_get(pt,'Z'),pc_get(pt,'value'),</div><div>FROM one_file_per_row,<br> PC_FilterBetween(<br> PC_FilterBetween(<br> PC_FilterBetween(point_cloud, 'X',2,3)<br><div> ,'Y',56,89)<br></div> ,'Z',21,42) as patch<br></div><div> , pc_explode(patch) AS pt<br></div><div>WHERE file_name = ....<br><br><br></div><div>Choosing a solution depends on a lot of factors,<br></div><div>pondering performances, storage, usage, facility to create, facility ot maintain, etc etc.<br></div><div><br></div><div>Cheers,<br>Rémi-C<br></div></div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">2014-12-02 21:07 GMT+01:00 George Merticariu <span dir="ltr"><<a href="mailto:merticariug@gmail.com" target="_blank">merticariug@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hello!<div><br></div><div>Thank you for your answer! </div><div><br></div><div>Please find below more information:</div><div><br></div><div>The type of data which I will insert is an 1D array of values between 0 and 255. </div><div>This array should be mapped to different dimensions: </div><div>1D - grey string</div><div>2D - grey image</div><div>3d - grey cube</div><div><br></div><div>There will be a lot of reads from the arrays and only one write at insert. The size of the array will be kept constant and will be given by the file size.</div><div><br></div><div>Is there a way to import directly the 1D binary file into arrays of higher dimensions or do I need to convert it first and then import it?</div><div><br></div><div>Best,</div><div>George <br></div></div><div class="gmail_extra"><div><div><br><div class="gmail_quote">On Tue, Nov 25, 2014 at 5:56 PM, Rémi Cura <span dir="ltr"><<a href="mailto:remi.cura@gmail.com" target="_blank">remi.cura@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div>Hey,<br>you don't even need postgis for this, you could store a cube per line,<br></div><div>with a x,y,z number, indexes on it,then querry like<br>SELECT *<br>FROM my_cube_table<br></div><div>WHERE x BETWEEN 100 AND 200<br></div><div>AND y BETWEEN 23 AND 45<br></div><div>AND z BETWEEN 45 AND 67<br></div><div>You could alos use postgres range type.<br></div><div>Of course you could store cube as meshes, and use pure 3D function (postgis so )<br></div><div>etc etc<br><br></div>It is very hard to answer you if you don't explain what you want to do with this cubes , how many you will have, ifyou read it more or write it more, what kind of data it contains, if the size of each cube may change, if you want to convert this to geo types ...<br><br>Cheers,<br></div></div>Rémi-C<br></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div>2014-11-25 17:32 GMT+01:00 George Merticariu <span dir="ltr"><<a href="mailto:merticariug@gmail.com" target="_blank">merticariug@gmail.com</a>></span>:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div><div dir="ltr"><div dir="ltr" style="font-family:arial,sans-serif;font-size:13px">Hello!<div><br></div><div>I want to use PostGIS for handling 3D cubes but I couldn't figure out how to do it from the manual. </div><div><br></div><div>The main tasks I want to accomplish are:</div><div><br></div><div>1. Import a 1D char array file (grey cube) into a 3D cube.</div><div>2. Retrieve sections from the cube, where a section is defined by a domain.</div><div><br></div><div>Example:</div><div><br></div><div>Given a file of 1024*1024*1024 bytes, I want to import it into a cube with the domain [0:1023, 0:1023, 0:1023]. Then, select the sub-domains (examples):</div><div><ul><li style="margin-left:15px"> [100:200, 100:200, 0:100]</li><li style="margin-left:15px"> [0:1, 0:1023, 0:1023] <br></li></ul></div><div><br></div><div>Is this possible using PostiGIS? If yes, are there any detailed tutorials which explain how to do that?</div><div><br></div><div>Thank you!</div><div><br></div><div>Best regards,</div><div>George Merticariu</div><div><br></div></div><div><div dir="ltr"></div></div>
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<a href="http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users" target="_blank">http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users</a><br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr">George Merticariu<div><br></div><div>Jacobs University Bremen</div><div>M.Sc. Computer Science </div><div>Class of 2016</div><div><br></div><div><a href="mailto:g.merticariu@jacobs-university.de" target="_blank">g.merticariu@jacobs-university.de</a></div><div><a href="mailto:merticariug@gmail.com" target="_blank">merticariug@gmail.com</a></div></div></div></div></div>
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