How can I get to the top Aggregate web services page?
Click on the Home icon in the upper right corner of each page.
What is the format of aggregate input file?
The first line of the input file has the following format voxels voxel_dim_x voxel_dim_y voxel_dim_z origin_x origin_y origin_z
where voxels is the numbers of input voxels, voxel_dim_x,
voxel_dim_y, and voxel_dim_z are the dimensions
(real numbers) of individual voxel in x, y, and z direction, respectively, and
origin_x, origin_y, and origin_z are the
coordinates (real numbers) of point which serves as the origin for
local coordinates of individual voxels. For each of the input voxels,
the line of the following format appears in the input file x y z mask
where x, y, and z are the integer non-negative
coordinates of the voxel (all voxels are assumed in the first octant)
and mask is the non-negative boundary mask (ranging from 0 to
63) in which the 6 least significant bits indicate whether the
particular voxel face is boundary (if the bit is set to 1) or is not
boundary (if the bit is set to 0). The individual bits are related to
voxel faces according to the following rules:
bit 1: face with outer normal pointing in the negative x direction
bit 2: face with outer normal pointing in the negative y direction
bit 3: face with outer normal pointing in the negative z direction
bit 4: face with outer normal pointing in the positive z direction
bit 5: face with outer normal pointing in the positive y direction
bit 6: face with outer normal pointing in the positive x direction
Voxels with zero mask are ignored unless all voxels are used with zero
mask in which case the mask is derived automatically for each
voxel. There are few example input files:
What shapes of aggregate particles may be handled?
There are generally only two limitations on the shape of an aggregate
particle. Firstly, there should be no internal voids in the particle. Secondly, the
aggregate particle has to be star-shaped with all boundary faces
visible from the voxel-based centroid which is used as the expansion center.
How can I get to the job results if I forgot the Aggregate job identification number?
If you had specified the email address when uploading the job you can find the
Aggregate job identification number together with URL of the results in the notification email
(if not deleted yet :-). Try to pick up the right message if you had processed more jobs.
If you had not specified the email address you have no chance to get to the job results at all.
How long is my job going to wait in the queue?
This is hard to say. The jobs are executed at selected times only. The number of executed Aggregate jobs
depends on the number of jobs in the queue. With respect to current setting of the queue manager
it could take from 1 minute to 2 hours. You can contact me
if your job is pending in the queue for more than 24 hours.
I am repeatedly trying to upload an Aggregate job each time with the same error message
There are now too many uploaded Aggregate jobs. Please, try it later !
Is there something wrong?
Maybe yes, maybe not. Either it is possible that someone is trying to overload the server or
(which is more likely) the queue manager does not work properly and the jobs are pending in
the queue without a chance to be processed. You can contact me
if you are likely to loose your patience soon.
I cannot upload even a very small job each time getting this error message
There is now too much disk space consumed by Aggregate jobs. Please, try it later !
What can I do about that?
Nothing. The disk space occupied by all the Aggregate jobs (also those being already processed and waiting
for removal either by the user or by the system) is limited. Until any of the jobs is deleted you
are not allowed to upload further one(s). You are therefore strongly encouraged to download the job results
to your local machine and to remove them from Aggregate server.
How large aggregate particle may be processed?
There are two restrictions. Firstly, the size of the uploaded file is
not allowed to exceed 300 kB. And secondly, the volume of the
rectangular bounding box of the aggregate particle is limited to 25
I bookmarked the page with the results of my successfully completed job but it seems to
not exist any more. When trying to display the results using the job identification number
I am getting this error message
Aggregate job 25213 not found
How can I get to the results?
The results of the job are stored at least for 3 days after its completion. After that
the job and its results are deleted by the system and the result page becomes invalid. Download
the job results to your computer within these 3 days if you intend to use them later.
My web browser does not display the output file of the completed Aggregate job. I have always to download it
to my computer. How can I view the output file without downloading it?
It seems that you are using MS Internet Explorer. You might experience a similar behaviour also for
other files produced by Aggregate web services and for the input file
as well. The problem is caused by associating a specific
software (application) to handle files with specific suffix. You may try a different web browser or to
deactivate the association with the appropriate suffix.
I cannot visualize the generated smooth representation of aggregate
particle in my web browser. By clicking on the VRML link on the
results page I see the VRML source only. Should I install some software?
Yes, you should install a VRML plug-in or an external VRML viewer (invoked for x-world/x-vrml mime type).
There are many VRML viewers available on the web.
(I am sorry, but the link to list of VRML viewers on www.web3d.org is not functional any more.
But you may consider to visit
The resolution of the smooth surface of the aggregate particle is
quite coarse. Is there a way to make it finer?
Unfortunately not. The tessellation of the smooth surface is fixed to
200 (longitudinally) by 100 (latitudinally) facets.
What is the meaning of numbers in the parenthesis on the first line of
the expansion coefficient output file?
The first number stands for the expansion order, the second and third
numbers refer to the integration orders in latitudinal and longitudinal direction,
There are missing some of the expansion coefficients (namely those for
negative m) in the output file?
Not really. The expansion coefficients a_nm for negative
m are obtained from the following relations:
Re(a_nm) = -Re(a_nM) for odd M > 0
Re(a_nm) = +Re(a_nM) for even M > 0
Im(a_nm) = -Im(a_nM) for even M > 0
Im(a_nm) = +Im(a_nM) for odd M > 0
where m = -M and Re(a_nm) and Im(a_nm) denote the real
and imaginary part of particular expansion coefficient a_nm.
What is the meaning of numbers in the parenthesis in the heading of
the output of geometrical properties?
The first two numbers denote the integration orders in latitudinal and
longitudinal direction, respectively, used for the evaluation of
expansion coefficients. The last two numbers indicate the integration
orders in latitudinal and longitudinal direction, respectively,
adopted for the evaluation of geometrical properties.
How are ordered the central moments of inertia on the output?
Due to the symmetry of the inertia tensor, only the components in its
upper triangular part are on the output. On the first line, there are the
diagonal entries I_xx, I_yy, and I_zz. On the second line, there are
the non-diagonal entries I_yz, I_xz, and I_xy.
The average Gaussian curvature is always almost one irrespectively what
is the shape of particle being processed. Isn't that wrong?
Quite contrary. This is the sign that the analysis is correct.
The average Gaussian curvature is equal exactly to one for all shapes
topologically equivalent to a sphere. This is also the case for aggregate
particles under consideration. The average Gaussian curvature can be therefore used
as an efficient indicator whether the applied integration order is
sufficient. On the other hand, however, it reveals nothing about the
appropriateness of the particular expansion order being applied.