LSPIV vs MARVLS
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
LSPIV
This application enables large-scale particle image velocimetry (LSPIV) using a smartphone. It offers a non-intrusive method for measuring water surface velocity distribution in both field and lab settings. The app provides instant ortho-rectification of captured images without needing ground control points.
- Large-scale particle image velocimetry
- Water surface velocity measurement
- Non-intrusive velocimetry
- Smartphone implementation
- Instant ortho-rectification
- No GCPs required
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LSPIV (large-scale particle image velocimetry) is an image-based method for measuring velocity distribution on the water surface. Applications of LSPIV have been increasing for both field and laboratory experiments as unique and powerful tools for non-intrusive velocimetry using conventional imaging devices and specialized image processing software. This app utilizes a smartphone to implement LSPIV. By innovatively combining the sensors embedded in smartphones, the images captured with them can be intrinsically and instantly ortho-rectified without making recourse to GCPs. The app was developed under support by the River Fund in charge of the Foundation of River and Watershed Environment Management (FOREM), Japan; Grant-in-Aid for Young Scientists (B); and the Research Fund of Japan Institute of Country-ology and Engineering.
MARVLS
Explore physics and math concepts with interactive augmented reality models. This app brings abstract ideas to life, allowing users to manipulate and understand complex topics through their phone. Requires a printable Merge Cube for an immersive learning experience.
- Augmented reality models
- Interactive physics concepts
- Merge Cube integration
- Topic navigation
- Model manipulation
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View augmented reality model of physics and math concepts through your phone. You'll need a Merge Cube (downloadable from the internet). Click on different button to navigate to different topics. Click on View in AR to view the model. Hold the Merge cube so that your camera can see it well. Move the cube around until you see the model. Click on the buttons to interact with the model. Click the back button to get back to the info screens or to the main screen.
Screenshots
Verdict
The clearest difference is ratings volume: MARVLS at 35 against LSPIV's 1. LSPIV's advantage is rating (5.0 vs 4.8). On price, update cadence, ads and in-app purchases there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
LSPIV holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: MARVLS has 35 ratings behind it against 1, so its average is the more settled of the two.
LSPIV ships an update every 13 months, MARVLS every 8 months. The most recent releases landed on October 22, 2026 and October 20, 2026 respectively.
| Parameter | LSPIV | MARVLS |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | 4.8 (35 ratings) |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | 1 | 35 — better |
| Update frequency | Every 13 months | Every 8 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 11.0 | 11.0 |
| Further details — not scored | ||
| Size | 71 MB | 208 MB |
| Age rating | 4+ | 4+ |
| Developer | Ryota Tsubaki | Michele McColgan |
Customer experience
LSPIV
MARVLS
In-app purchases
LSPIV
No in-app purchases
MARVLS
No in-app purchases
