A while ago I wrote about high quality shadow filtering, and in particular about how to approximate a Gaussian using bilinear taps. Today I just noticed the following in the third edition of Real-Time Rendering:
Alternatively, the Gaussian could be approximated by using a bilinear interpolated sample for every four texels, finding the offset that gives the closest approximation to the ideal weights.
So, I guess I was not saying anything new after all.
I’ve been thinking about writing about cooking in this blog for a while. Not just to share what I’ve learned, because, well, I don’t have much to share, but to get other people’s ideas and suggestions. While I may cook better than the average American and may be able to impress my wife and friends, I’m not really such a good cook. I know how to follow recipes, and I’m starting to get some sense of what works and what does not, but I have a lot to learn, which is actually fascinating; there’s a whole world of flavors out there and exploring it is a very rewarding experience.
The results of my MRI arrived last week and confirmed my suspicions. I have a herniated disk that’s pinching the sciatic nerve. The really bad news is that my disk is in very poor shape, it’s flattened and dessicated. So, the road to recovery, if at all possible, will be long and slow.
I guess that runs in the family, both my mum and my uncle had the the same problem and had to get surgery to have their last vertebrae fused. The only difference is that this happened to me 10 years sooner.
Today there are some cool treatments that are administered to people that have high chances of recovery and that accelerate the healing of the disk by injecting ozone between the vertebrae to encourage rehydration.
I still haven’t heard anything from the spine clinic so I don’t really know what options do I have available or what do they recommend. That is a very common procedure in Spain, so I’m hoping they will give me that option here too, but so far I’ve been very disappointed with my medical care, so I don’t have high hopes.
I don’t really want to do surgery. The post-operatory recovery sucks. I would have to wear a corset to immobilize my back during three months and spend most of that time prostrated in bed, but the prospect of chronic pain is not very encouraging either.
My pain persists as usual and I have a new symptom: I stopped feeling the left side of my leg recently. It’s numb, just the same way you feel your mouth after the dentist. On the other side I’m getting used to this condition and learning how to deal with it more effectively. So, I guess you could say I’m feeling a bit better.
Our siggraph course has been accepted and is finally up on the siggraph website! Here’s the brief description of the course:
An overview of the most recent theoretical results and their implementations on the current and next-generation GPUs, and a demonstration of applications in the gaming and movie industry.
We will bring together participants with different backgrounds: ISV from the game and movie industry, IHVs and academia. Each one will provide their own point of view on the topic and describe their own experiences with these methods. I think that will be very valuable to understand the weaknesses and strengths of these techniques, and will hopefully encourage other developers to adopt them.
Yes, this is another post about the progression of my health.
As I lowered the dose of prednisone last week the pain intensified, and if having constant pain wasn’t enough I also started to suffer insomnia. For some reason the pain is worse when lying or sitting, which means that I cannot get any rest. During the night the pain builds up until it’s so strong that it wakes me up. Initially I started waking up 4 to 6 hours after falling asleep, but it got worse during the week and at some point I couldn’t sleep more than 2 hours straight.
I started going to this chiropractor and I think she is pretty good. I haven’t been to a chiropractor before, so I don’t have any previous experience to compare her with, but she does massages in addition to spinal manipulation, and her massages are the bests I have ever received. She also had a great suggestion for my sleep problems: to sleep facing down with a rolled towel or thick pillow under the left side of my pelvis. That worked pretty well allowed me to sleep about 6 hours again.
The pain and the sleep deprivation is starting to take a toll on me. I’ve given up on trying to work. I’m unable to focus and was doing a crappy job anyway; the only thing that I was achieving was to hurt myself. My doctor is starting to think I may need surgery. He wants me to get back on prednisone and to start taking stronger opioids. I really don’t want to repeat the same cycle of euphoria and depression. These drugs mess my head too much and I’m already prone to psychotic breaks. I’m finally going to do an MRI on Wednesday in order to decide what to do next.
My mother thinks I should go back to Spain. The only thing that really keeps me here are Mariana’s studies.
I love this quote from Ivan-Assen Ivanov about the NVIDIA Texture Tools:
We switched to CUDA nvcompress in our pipeline and totally forgot
about it. Until yesterday, when an artist had to work on a 7600 for a
while, and raised hell about how slow the export has become.
:-)
So, I finally bought the Ikea standing desk and I’ve been using it full time during this week.
As many predicted my feet hurt, and at the end of the day I feel extremely tired, almost as if I had been hiking, which is actually quite a nice feeling. For once I now get to sleep before midnight and wake up early in the mornings. I’ve realized I have to do stretching exercises to prevent cramps during the night. I suppose my body will end up getting used to it.
My doctor has finally prescribed me some stronger drugs. I’m now taking Prednisone for the inflammation and Vicodin for the pain. During the first few days the Vicadin eliminated the pain entirely; after weeks of constant pain with some acute episodes that was quite a relief. I felt energized and euphoric, suddenly I could walk normally, I could even run, jump, speed up my bike, and get some adrenaline flowing!
Unfortunately the body creates tolerance fairly quickly, so I had to reduce the dose. However, I think the inflammation is finally receding, the pain is still there, but it’s just a mere discomfort. I think the results of the physiotherapy are also starting to show. The S shape of my column has been corrected, it feels much more straight now. My abs are stronger than ever. I’m not sure it has been of any help for the pain, but at least it will hopefully prevent more damage in the future.
Spending most of the day seated seems to aggravate my sciatic pain. The pain is worst when standing up after spending a few hours seated in the same position. One solution that I’ve found is to work standing up; it was a bit tiring initially, but one quickly gets used to it and any discomfort is outweighed by the absence of pain.
However, I don’t have a standing desk. So, I’ve improvised a temporary solution using the wall unit in my living room. It works well, but it’s less than ideal. There’s no room for legs, the keyboard is slightly lower than I would like and the screen is a bit too high.
I’ve been looking for a reasonably priced standing desk without much success. Ikea used to have one, but they don’t carry it anymore. I’m looking for something like their Galant desk, but with adjustable heights of up to 42”.
Steelcase has something that’s pretty close to that, but at the whooping price of $749.00, and it only reaches 41”.
I really like the WorkRite Sierra rectangular desk, but I haven’t been able to find it for much less than $1,200, which is just too much.
GeekDesk sells adjustable frames for $550, and while it seems to have good reviews, it doesn’t inspire me much confidence.
Do you have any recommendation?
The slides of the GDC tutorials are already online. I was not at GDC on Monday and Tuesday, so I just gave them a quick glance to see if there was anything interesting.
One that caught my attention was AMD’s presentation on high quality shadow filtering. It seems that most of the talk was dedicated to showing that Gaussian shadow filtering looks better than uniform, and that the former can be implemented much more efficiently by using Gather4.
In particular, they claim that with Gather4 it’s possible to sample a N x N kernel in (N-1)*(N-1)/4 samples, and that using bilinear filtering you need to at least use (N-1)*(N-1)/2. That has a bit of truth, but it’s not entirely correct.
Yesterday I released another revision of the stable branch of the NVIDIA Texture Tools. I recommend everybody to upgrade, since it fixes some bugs and artifacts, and improves compatibility with current and future CUDA drivers. Starting with this release I’m planning to provide a verbose description of the changes in each release. So, here it goes:
I’ll be at GDC next week from Tuesday to Friday. I’ll be there to meet the usual suspects and some new faces. I won’t have conference pass, so I guess that the rest of the time I’ll be wandering through the expo hall or sitting on a corner coding on my laptop.
If you want to find me, I’ll be at the NVIDIA booth on Wednesday from 11:30 to 2:00, and on Thursday from 2:00 to 3:30. Booth duty is generally pretty boring. So, please pass by to say hi, and chat about tessellation, graphics apps for compute, texture compression, or any other topic that you would like.
Note that like last year, NVIDIA won’t have a booth in the show floor, but an expo suite hidden in the West Hall. You won’t find it, unless you look for us!
Even thought the DXT compression format is widely adopted, most of the hardware implementations use a slightly different decompression algorithm.
The problem is that there never was a specification that described the preferred implementation. The DXT format was first documented by S3 in US patent 5956431. However, in order to cover all possible implementations the description in the patent is very generic. It does not specify when or whether the colors are bit expanded, or how the palette entries are interpolated. In one of the proposed embodiments they approximate the 1/3 and 2/3 terms as 3/8 and 5/8, which would have been a good idea, if everybody had chosen the same approximation. However, different implementations approximated the expensive division in different ways.