Geoid Calculator vs BluTech
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Geoid Calculator
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Undulation Calculator is a powerful tool for geodesy professionals, surveyors, pilots, engineers, and anyone working with GPS coordinates and elevation data. Calculate geoid undulation (the difference between Mean Sea Level and the WGS84 ellipsoid) at any point on Earth with precision and ease. Calculate the geoid undulation (N value) at any location using the official EGM96 (Earth Gravitational Model 1996) dataset. Understand the relationship between the geoid (Mean Sea Level) and the WGS84 ellipsoid used by GPS systems. Get precise terrain elevation information using the ETOPO1 global relief model with 1 arc-minute resolution (~1.8 km). Includes both land elevations and ocean bathymetry data. Easily convert between three altitude reference systems: - MSL (Mean Sea Level) - Height above the geoid - HAE (Height Above Ellipsoid) - GPS altitude relative to WGS84 - AGL (Above Ground Level) - Height above terrain Explore a stunning 3D visualization of Earth showing: - Color-coded geoid undulation map (blue for positive, red for negative) - Accurate terrain geometry with realistic lighting - Ocean bathymetry visualization - Rotate, zoom, and explore the globe interactively Visualize geoid undulation and terrain elevation along longitude and latitude cross-sections: - Interactive charts showing geoid (MSL) and terrain (HAE) surfaces - Current location marker - WGS84 ellipsoid reference line - Easy-to-read axis labels with unit conversions Enter coordinates in multiple formats: - Decimal degrees: (48.8566, 2.3522) - Degrees with cardinal directions: 48.8566°N, 2.3522°E - Paste directly from Apple Maps or Google Maps - Automatic coordinate parsing and validation Switch between meters and feet for all elevation values, with precision appropriate to each measurement type. Uses official geodetic datasets: - EGM96 geoid model (15 arc-minute resolution) - ETOPO1 terrain model (1 arc-minute resolution) - Bilinear interpolation for sub-grid accuracy Perfect For: - Surveyors and geodesy professionals - Pilots and aviation professionals - Engineers working with GPS/GNSS data - Students studying geodesy and cartography - Anyone needing to understand the relationship between GPS altitude and sea level Technical Details: - EGM96: Earth Gravitational Model 1996, the international standard for geoid undulation - ETOPO1: Global 1 arc-minute relief model covering land and ocean - WGS84: World Geodetic System 1984, the standard GPS coordinate system - All calculations performed locally on-device for privacy and offline use GPS devices report altitude relative to the WGS84 ellipsoid (HAE), but most real-world applications need height above Mean Sea Level (MSL). The difference between these two surfaces is called "geoid undulation" and varies from location to location, ranging from about -106 meters (Indian Ocean) to +85 meters (Iceland). Understanding this relationship is crucial for accurate elevation measurements.
BluTech
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BluTech is a technician app designed to streamline deployment operations enabling customers to setup readers and/or change configuration with a seamless and user - friendly interface. It is geared towards amusement market as part of this release. Deployment: Simplified user experience to create locations and rooms without ever having to login to the back-end management system. Define the settings for the machine and send the configuration directly to the reader. Cash Collect: Collect the cash transaction data from readers and upload to server. Service: Send some commands to readers via Bluetooth to get the information or do some operations. Signal Test: Test the WiFi/Cellular of the routers to which readers connect to. *Device Permissions* When you use the BluTech app, the following permissions may be requested. - Local network: To find and connect to the server. - Bluetooth: To connect to the readers to send and collect data.
Screenshots
Verdict
The clearest difference is iOS requirement: BluTech at 13.0 against Geoid Calculator's 18.5. On price, ads, in-app purchases and device support 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.
| Parameter | Geoid Calculator | BluTech |
|---|---|---|
| Price | Free | Free |
| Update frequency | — | Every 2 months |
| Ads | No | No |
| In-app purchases | No | No |
| Devices | iPhone, iPad | iPhone, iPod |
| Requires iOS | 18.5 | 13.0 — better |
| Further details — not scored | ||
| Size | 450 MB | 46 MB |
| Age rating | 4+ | 4+ |
| Developer | Joshua Manson | PayRange Inc. |
In-app purchases
Geoid Calculator
No in-app purchases
BluTech
No in-app purchases









