New Feature : SharpSolve - SharpCap's new built-in plate solver

[s2a]

Ok, thank you both very much for the information! Best regards; R

[Ronbo]

Hi this is my first post so pardon me if I am 2 or 3 centries behind.
I can't find sharp solve. I have SharpCap 4.0 running and I have ASTAP loaded I just can't get it to work so I thought I would try SharpSolve but in the drop down my options are only ASTAP and Astrotrotilla
So any guidance would be appreciated

ron

[admin]

Hi Ron,

sorry for the delay in approving your post and replying - somehow it vanished from the list that I usually use to check for that sort of thing, and I only just found it.

You need to upgrade to SharpCap 4.1 to get SharpSolve - in fact you need to make sure you are updated to a fairly recent version of 4.1, since it wasn't in the very earliest versions of 4.1. SharpSolve has never been in SharpCap 4.0 at all.

cheers,

Robin

[Ronbo]

I figured it out about 5 minutes after I showed my ignorance to the whole world of course.

Thanks for your kindness
ron

[Diogenes505]

Hi folks,

another update to SharpSolve today

I have updated the default plate solving index file to one generated from the Gaia catalog rather than UCAC4. Using the Gaia data helps avoid sparse areas in the index which could lead to problems with plate solving - in my testing, the catalog update alone reduced the failure rate at 0.5 by 0.5 FOV by over 60%.

I've also now got an index for solving down to 0.25 by 0.25 (actually works a bit below this, but the success rate drops rapidly between about 0.23 and 0.20 degree FOV). This new index file is about 160Mb and does not compress, so it is not included in the default install. There is a button on the plate solving settings to download it.

If you need to install the larger index on a PC with no internet access then the download is here - https://downloads.sharpcap.co.uk/psinde ... x.0.25.bin. Copy the downloaded file to the target PC and use the 'Browse for Index File...' button in the settings to select it. SharpCap will make its own private copy of the file.

Once the new index file is installed either by direct download in SharpCap or manual download and browsing for the file, the option to make SharpSolve search down to 0.25 degree FOV will become available. This makes plate solving operations about 4 times slower (four times more data to search), so it is not worth using unless you really are working at small FOV.

To go along with these updates, I have re-designed the Plate Solving settings page of the settings - see below

Screenshot 2023-11-13 120131.jpg

Hopefully this makes the page easier to understand and use. Key changes are

* The test button moves next to the plate solver selection drop down.
* The selection drop down shows 'not available' after the names of plate solving engines that SharpCap did not detect as being installed
* The settings for individual plate solving engines are now in tabs that you can look through at the bottom, rather than magically appearing when you selected a particular engine
* The detection results for each engine are shown in the tab alongside other settings for the engine
* Settings not related to a particular plate solving engine are grouped in a 'General' box (maybe I will rename that to 'General Plate Solving Settings'.

Hope this makes sense! Happy plate solving!

Robin

This is just what I needed but the download button is giving me fits. My SharpCap version is up to date but I get an error message.
Plate solve index download failed.
Response status code does not indicate success: 429 (Too many requests)
I am doing something wrong can you please help.

[admin]

Hi,

I don't think it is anything you are doing - the error code sounds like it is just the hosting provider who I use for downloads blocking the download due to too many requests to download the file. One of the things that seems to be happening a lot at the moment is that the forums are being scanned repeatedly by AI training bots, which download everything they can find - this puts a high load on the servers and can lead to failures of this sort. Sometimes it gets so bad that the whole forum becomes slow and unresponsive and I have to go and block a group of IP addresses (usually from China) to stop the load.

Worth trying again in the download button in SharpCap, or otherwise use the manual download link that is in the post you have quoted above.

cheers,

Robin

[admin]

Some recent posts here on the forums about issues with the download for PlateSolve3 and other challenges with plate solving got me working on the SharpSolve plate solving engine again. I have made more improvements to performance (some already in 4.1.13484, some still to come). These improvements are particularly noticeable if you have a modern CPU with lots of cores - SharpSolve is now much more efficient at using multiple cores leading to better performance on CPUs with 4 or more cores.

I have also been looking at the limits in terms of the smallest field of view that SharpCap works at. Rather than try to go out and capture images at lots of different fields of view, I have been testing by using images at a larger field of view and cutting them down to the field of view of interest. For example, a single image taken with an IMX571 camera at 350mm focal length gives an FOV of about 3.9 by 2.6 degrees - this can then be split up into about 40 separate images each with an FOV of 0.5 by 0.5 degrees, and those images can be tested to see if they solve or not. Repeat with 0.45 squares, then 0.40 degrees and so on and you can see how the plate solving works at different image sizes.

For the test I used two selected test images - both deliberately picked because they are of a rich star field, so plenty of stars in the image even when cutting out small areas of the image. Rich fields were chosen to ensure we are testing the plate solving engine and index, not testing whether there are enough stars in the test image. One image was at the 3.9x2.6 degree FOV mentioned above, the other at 0.73x0.49 degrees (IMX571 at ~1800mm focal length). The larger image is used to test larger fields of view and the smaller default SharpSolve index while the more zoomed in image is used to test smaller fields of view and the larger SharpSolve indices.

Ok, enough about the experiment setup, here's the results (discussion to follow)

PlateSolveSuccessRates.jpg (130.61 KiB) Viewed 2279 times

Let's talk through the four lines on the graph

1. Blue - this shows results with the default star index that is installed with SharpCap (labelled as supporting down to 0.5 degree FOV). Tests performed using areas cut from the larger FOV (3.9x2.6 degree) image.
   
   Measurements were only made at 0.5 degree FOV size and below, and even the default index performs pretty much perfectly with 100% solve rate down to 0.45 degrees FOV. It's probably still usable at 0.4 degree FOV with solve success percentages still in the high 90s, but below that point the success rate starts to drop off rapidly. I was actually surprised that it still manages to solve nearly 20% of the time when the FOV is 0.25 degrees, but I wouldn't want to try to use that database for real at that FOV.
2. Orange - this shows results with the high resolution SharpCap star index that is an optional download (labelled as supporting down to 0.25 degree FOV). Tests performed using areas cut form the smaller FOV (0.73x0.49 degree) image.
   
   The change to the higher resolution index works better than expected, with 100% success down to just below 0.2 degree FOV rather than the 0.25 expected. Again the drop off in success percentage as the FOV goes below this level becomes rapid, with the success rate falling to near zero at 0.1 degree FOV.
3. Yellow - this partial curve shows results with the high resolution index but using areas cut from the larger FOV image.
   
   This curve is using the same index as the orange curve, but the success rate drops off much sooner - once the FOV goes below about 0.3 degrees. This shows the limitations of the *image* - in particular, the shorter exposure and shorter focal length means that there are just not enough visible stars in the smaller areas being cut out at these smaller FOVs, and that lack of stars in the image is causing plate solving failures
4. Grey - this is using a new, unrelease, ultra high res plate solving Index that I have been working on. Tests performed using areas cut from the smaller FOV image.
   
   This one is very promising, since the success rate is 100% down to 0.12 degrees, 99% at 0.11 degrees and a fairly usable 95% at 0.10 degree FOV. Assuming that these figures are typical when testing other areas of the sky (assuming long enough exposure to see sufficient stars in such a small FOV) then this is at or close to the limits for any current plate solving software as far as I can see.
   
   As this index is considerably larger (about 620Mb), there is more work to do to check all the possible solutions, so the plate solving process is slower. A full sky search with this index may take a several minutes on a single CPU core, but could be as fast as 30 seconds or less on a really fast CPU with lots of cores. Obviously, if the approximate co-ordinates are known then the calculations will be much, much quicker.

So, the result of this is that within the next couple of weeks I hope to release a new update of SharpCap that will (with the new ultra high res index download) allow plate solving down to 1/10th to 1/8th of a degree FOV

As a final note - plate solving success depends on finding plenty of stars in the image to be solved, and this becomes particularly challenging at smaller fields of view. If can only see a few fuzzy faint blobs in the image then it probably won't plate solve even with the world's best plate solving engine or the most complete star index. Good focus, steady tracking and longer exposures (up to 60s or perhaps even more) may be needed at small fields of view to ensure enough stars can be detected in the image for good results.

cheers,

Robin

[admin]

Hi folks,

I have just uploaded a new SharpCap update (4.1.13534) which includes the option to download and use the new 'Ultra Hi Res' plate solving database mentioned in the post above. This should solve images down to at least 0.12 degrees (1/8th degree) FOV and probably as far down as 0.1 degrees - provided that there are enough visible stars in the image (at least 20+). At such small fields of view, getting enough stars may require exposures of 30s, 60s or even longer. Even with long exposures, there are some areas of the sky where stars are very sparse, and solving down to such small FOV sizes may just not work at all in those areas.

To configure the new index, go to the plate solving settings and first click the 'Download' button in the bottom row to download the new index, then check the 'Active' button on the left of that row to make the new index active

Screenshot 2025-07-28 105344.jpg (80.71 KiB) Viewed 2211 times

A few things to note:

* The new 'Ultra Hi Res' index can only be used on the 64-bit version of SharpCap - it needs too much memory for it to work reliably in the 32 bit version

* Plate solving times (particularly for whole sky searches) will be slower using the ultra hi-res index. As a rule of thumb, expect the time taken to multiply by about 4 compared to the 0.25 degree 'Hi Res' index and about 16 compared to the default 0.5 degree index.

* If you have 4 or more cores on your CPU, SharpCap will use them to speed up plate solve operations. With only a single CPU able to work on the plate solve (2 core or less CPU) then a full sky search with the new index may take 5 minutes or more. I have an AMD 7950X which will complete a full search (using 24 or 32 cores) in 14s. YMMV.

* The new index is split into smaller sub-areas than either of the other 2 - this helps keep memory usage from being excessive, but means that it might struggle at very large fields of view (say above 5 degrees or so.)

cheers,

Robin

[RMSQueenMary]

So many new features. I would like to try Ultra Hi Res plate solving.

[PeterC65]

I'm struggling to download from the SharpCap site. Downloads stop after about 10MB due to a network error. I can restart them and after doing this many times I managed to download v4.1.13651, but the same problem is stopping me from downloading the much larger Ultra Hi-Res data file for plate solving.

There doesn't seem to be a problem when I try to download from other sites.

Peter