fredvanner
Well-known member
Even with reasonable bandwidth, a 60+GB download takes a while!My desktop is sweating and griping
Even with reasonable bandwidth, a 60+GB download takes a while!My desktop is sweating and griping
Here's the No Drizzle screenshot:I'm getting an error when applying SPCC:
Robust linear regression (R/G): 0%
*** Error: Insufficient data: only 1 sample(s) are available; at least 5 are required.
Reading swap files...
2654.501 MiB/s
<* failed *>
I've attached a screenshot. I have no idea what setting(s) might address this - I would greatly appreciate some help, thanks!
More info: it's a 2x Drizzled image from WBPP; the non-drizzled image gets processed by SPCC just fine (see second screenshot). Is there a workaround?
I have been trying this for the L-Pro but the new filters never show up in the drop down menus. Any idea what I am doing wrong?Although the Optolong L-Pro is on the "Curve Explorer" (CE) list, it is not obvious (from the documentation) how to use it. Is this the correct process:
- in CE, find and select the best match to your camera R filter
- in CE, find and Ctrl-click the Optolong L-Pro ("PAN") filter
- click on the View attachment 16545 icon to combine and create and name a new combined R filter
- repeat for G and B filters
- select the combined filters from the R, G, B dropdowns
When exiting the CE window, click OK and then click to save the newly defined filter combinations.I have been trying this for the L-Pro but the new filters never show up in the drop down menus. Any idea what I am doing wrong?
Len
I think I have been doing this but I will try again. Thanks!When exiting the CE window, click OK and then click to save the newly defined filter combinations.
Thank You for this Fred.I'm afraid the GAIA and APASS processes are more recent than "Inside Pixinsight".
It is worth undersanding how they work. They both replace on-line searches using the VizieR interface. Instead they implement efficient local searches of a downloaded version of the key databases with files in the proprietary .xpsd format.
To use these local databases, you must first download the necessary database files, which you can place anywhere you like on your system.
The PCC process requires the APASS data files DR9 and/or DR10 (about 3GB for both files). Because the coverage is not complete in either of these databases, I suggest that you download both if you intend to use PCC. PCC is superseded by the SPCC process. This uses a GAIA database with enhanced spectral data, the DR3/SP files. The full data set comprises 20 files totalling about 63GB; some trial and error may be required to find just how many you need, which will vary from image to image. The ImageSolver script should use the GAIA DR3 files, which are different to the DR3/SP files. These comprise 16 files totalling about 40GB.
Once you have downloaded the files, you must run the APASS process (to locate the APASS DR9 and DR10 files), and the GAIA process (to locate the DR3 and DR3/SP files). The process for specifying the file locations is the same for the APASS and GAIA processes:
Executing the APASS or GAIA processes requests a database search (with the parameters specified in the dialogue). The resulting list of sources can be output to a file, if a file is specified. If no file is specified, a summary is output to the process console. This can be usefull as a quick "reality check" of how many sources there are in a region.
- first, select the "wrench" icon on the bottom bar of the process.
- In the pop-up preferences window, select the data release dropdown and select which data release you are going to specify (e.g. "Gaia DR3/SP")
- now click the "select" control and navigate to the folder with the required files
- now select all the files required (using the multiple file select funtion of your operating system)
- select "open" (in Windows, or the equivalent control)
- the selected files will now be displayed in the database files window of the preferences dialogue
- Repeat the above process for any other downloaded data release (e.g. "Gaia DR3")
- you can then close the APASS / GAIA process - you do not need to execute it (globally or otherwise)
So I guess I have to drizzle my images first ?Another important point when working with OSC cameras is to always use drizzle. Besides the fact that only a drizzle integration can provide optimal results by avoiding interpolation, some de-Bayering algorithms may modify color proportions at small scales, where interpolation of missing color data in CFA patterns plays an important role. This is the case with VNG. While large–scale structures remain untouched, point sources (like stars) will be altered. And, what is worse, this color shift depends on the sizes of the stars so that each image can be altered differently. This affects stellar photometry so that de-Bayering can lead to unexpected erroneous results, both with PCC and SPCC.
In practice, it is unlikely that your choice of filters will make a noticeable difference in the color calibration. You can likely get away with any of the OSC filter choices and be fine.Ok, I want to give a try to SPCC. I have a EOS 500D with the the LPF-2 filter removed and an Astronomik L2 UV/IR block filter.
Since the 500D is an OSC, i choose Ideal QE Curve. But what should i choose for the filters ?
The Canon EOD 500D R, G and B filters proposed seems to be for an unmodded 500D.
Should I use the Canon Full Spectrum filters ? And combine them with a UV/IR block filter, which are not proposed in SPCC.
And another question : in the SPCC's doc it is recommended to always use drizzle with SPCC :
So I guess I have to drizzle my images first ?
You don't have to drizzle. If you have enough well-dithered frames you are advised to drizzle (x1).I guess I have to drizzle my images first
Ok I will try with EOS 500 et Full Spectrum filters. Thanks you !In practice, it is unlikely that your choice of filters will make a noticeable difference in the color calibration. You can likely get away with any of the OSC filter choices and be fine.
Personally, I have almost never seen the slightest improvement from using drizzle given even a small degree of oversampling. I think the argument is more theoretical than practical. YMMV, but I'd suggest experimenting. And certainly, not bothering with it while you're trying to figure out your best SPCC settings.
I didn't even know that x1 drizzle was a thing.You don't have to drizzle. If you have enough well-dithered frames you are advised to drizzle (x1).
The reason for using x1 dither with an OSC is that it avoids the interpolation required in the debayer process - but the difference is not dramatic, particularly if the image is oversampled (in which case the inherent PSF spread has much the same effect as the debayer interpolation).
If your image is significantly undersampled (e.g. if running FWHMEccentricity gives an FWHM < 2 pixels) then x2 drizzle can increase the effective resolution of your image. The improvement will depend on just how undersampled you are. Note that this refers to the actual sampling (not the theoretical resolution). In the UK even images with sub-pixel thoretical resolution are almost always limited by the seeing conditions - hence my advice to use FWHMEccentricity to check your actual sampling PSF. You will also need more well-dithered frames for x2 drizzle (I don't think there is any documented way of estimating the number of frames required, but I'd aim for at least 50 for x2 drizzle).Is there a benefit to x2 drizzle
I just checked, my FWHM is 2.3px on Moffat4 stars. I will give a go to x1 drizzle then.If your image is significantly undersampled (e.g. if running FWHMEccentricity gives an FWHM < 2 pixels) then x2 drizzle can increase the effective resolution of your image. The improvement will depend on just how undersampled you are. Note that this refers to the actual sampling (not the theoretical resolution). In the UK even images with sub-pixel thoretical resolution are almost always limited by the seeing conditions - hence my advice to use FWHMEccentricity to check your actual sampling PSF. You will also need more well-dithered frames for x2 drizzle (I don't think there is any documented way of estimating the number of frames required, but I'd aim for at least 50 for x2 drizzle).